Studies of Reactions of Some Carbonyl Bridged

Home , Dicyclopentadiene

STUDIES OF REACTIONS OF

SOME CARBONYL BRIDGED COMPOUNDS WITH IRON PENTACARBONYL

LAI Chi-hung ( 黎志雄）

A thesis submitted in partial fulfillment of the

requirements for the degree of

Master of Philosophy

The Chinese University of Hong Kong

1978

Thesis Committee:

Dr. S. W. Tam, Chairman

Dr. K. H. Wong

Dr. T. Y. Luh

Prof. A. J. Birch, F. R. S., External Examiner

ACKNOWLEDGEMENT

The author wishes to express his gratitude to his

supervisor, Dr. S. W. Tam, for his invaluable instruction

and continous encouragement throughout the course of this

rsearch and the perparation of this thesis.

He is indebted to Dr. T. Y. Luh, Dr. T. L. Chan, and

Mr. T. C. Chiang for their helpful discussions during this

investigation.

His sincere thanks are also due to Mr. Y. H. Law and

Mr. S. C. Wong for their assistance in the measurements of

nuclear magnetic resonance spectra and mass spectra, respectively.

LAI Chi-hung

Department of Chemistry

The Chinese University of Hong Kong

May, 1978 11 SUMMARY

The reactions of iron pentacarbonyl with a series of

carbonyl bridged compounds, viz, 3a,4,,7,7a-tetrahydro-4,7-. methanoindene-l,,8-dione (6),.2, L4-dibromo-3a,,4,7, 7a-tetra-

hydro-4,,7-methanoindene-l,,8-dione (32), 4,5, 6, 7-tetraphenyl-

3a, 4, 7, 7a-tetrahydro-4,,7-methanoindene-8-one (33) and octa-

chloro-3a,4,.7,7a-tetrahydro-4,7-methanoindene-1,8-dione (39)

have been investigated Treatment of (6) with iron penta-

carbonyl afforded l-indanone. By using deuteriated compound

(21), the course of reaction was shown first to undergo

decarbonylation of the initial compound giving rise to 3a,7a-

dihydroindenone (8) which was then catalyzed by iron penta-

carbonyl,to undergo 1,3-hydrogen shift to yield l-indanone.

Treatment of (32) with iron pentacarbonyl 'gave 4-bromo-l-indanone

(55). The reaction was shown to undergo decarbonylation of

the initial compound to give 2,, L--dibromo-3a, 7a-dihydroinden one

(54),.and iron pentacarbonyl catalyzed rearrangement of double

bond to give 2,4-dibromo-l,indanone (57), similar to that as

described for compound (6), followed by. subsequent debromination

of (57) by iron pentacarbonyl to yield (55).

The reaction of (33) with iron pentacarbonyl produced

two iron carbonyl complexes, viz, tetraphenylcyclopentadienone-

iron tricarbonyl (60) and dicyclopentadienyldi-iron tetracarbonyl

(4). These complexes were formed due to the fact that (33)

underwent dissociation-to give tetraphenylcyclopentadienone (59)

3 and cyclopentadiene rather than decarbonylation to give the 3a,7a- dihydroindene derivative (34). As a result, (59) and cyclopentadiene reacted individually with iron pentacarbonyl to yield the corresponding complexes (60) and (4).

Compound (39) reacted with iron pentacarbonyl to give hexachloroindenone (61). However, the role that iron pentacarbonyl played in such reaction was unclear.

4 CONTENTS

Acknowledgement ii

Summary iii

Introduction 1

Research Plan 5

Results and Discussion 16

Experimental 32

List of Spectra 51

References 80

5 INTRODUCTION

Although the complex of platinum(II) with endo-dicyclopentadiene has been prepared by Hofmann and von Narbutt in

1908,1 and'its structure has been established as (1) by X-ray crystallography in 1961,2 the analogous complex of iron carbonyl (2) is still unknown in literature. Indeed, unconjugated dieneiron carbonyl complexes were not so commonly known as compared to,conjugated dieneiron carbonyl complexes.3 A well- known reported example4 of the former is thricarbonyl complex of 1,5-cyclooctadiene (3). The initial objective of this investigation. was to attempt the synthesis of the iron carbonyl

complex (2).

Fe(CO).

Pt Fe

ci Cl co co co

(1) (2) (3)

It sould be noted that (2) cannot be synthesized directly

from dicyclopentadiene and iron pentacarbonyl, because the

reaction would lead to dicyclopentadienyldi-iron tetracarbonyl

(4) as previously reported.5 1 CO CO

Fe Fe

CO co

(4)

A synthetic approach to (2) is outlined in Scheme I

where 3a,4,7,7a-tetrahydro-4,7-methanoindene-1,8-dione (6)6

was employed as the precursor with the hope that the corresponding

iron carbonyl, complex (7) was formed, which was then subjected to reduction to yield the desired complex (2).

Br Br

HOCH2CH2OH 2Br7/dioxane NaOH/CH30H, H

spontaneous Fe(co)5 70% H.,SO4 ?

(5) (6)

Z n/HC l

Fe ? Fe

Co CO CO CO CO Co

(7) (2)

Scheme I

2 Experimental results showed that only starting material

(6) was recovered after a cyclohexane solution of (6) and excess iron pentacarbonyl had been heated under reflux in a

nitrogen atmosphere for ca. 24 hours. However, the xylene or

dioxane solutions of (6) and excess iron pentacarbonyl in

similar reactions yielded l-indanone as the isolaable product.

Fe(CO)

Fe(CO) xylene

Although the synthesis of the desired complex (7) was

unsuccessful, the isolation of l-indanone from the reaction

mixture was striking. Decarbonylation of (6) should give rise

only to 3a,7a-dihydroindenone (8), and one cannot readily

rationalize the facile rearrangement of the double bond from

(8) to l-indanone. Furthermore, thermal suprafacial concerted

1,3-hydrogen shift is a "forbidden" process according to the

Woodward and Hoffmann rules.7

3 An explanation for the formation of 1-indanorle from

(8) may be offered in terms of the formation of the intermediate organometallic complex such as that indicated below where the presence of the iron atom allows the suprafacial 1,3- hydrogen shift to occur thermally.

Fe Fe

In order to establish the proposed mechanism, part of the work described in the following sections is devoted to mechanistic studies for the tranformation in question, and

the rest is concerned with the synthesis of several analogous

carbonyl bridged compounds and the studies of their reations

towards iron pentacarbonyl.

4 RESEARCH PLAN

Ⅰ. Mechanistic Studies:

As described in the previous section the reaction of

3a,4,7,7a-tetrahydro-4,7-methanoindene-l,8-dione (6) with iron pentacarbonyl afforded l-indanone. One possible mechanism for such transformation is outlined in Scheme.

The migration of the double bond catalyzed by iron pentacarbonyl

is proposed to occur via the ustable (olefin)-Fe(CO)4 intermediate (9). Upon allylic hydrogen abstraction to form the -allyl-hydroiron tetracarbonyl (10), the bridgehead hydrogen (H3a) is shifted to the C2 position where another

(olefin)-Fe(CO)4 (11) is formed. In a similar fashion, the bridgehead hydrogen (H7a) is moved to the C3 position resulting

in the formation of the l-indanone (12).

H3a

H3a H3a Fe(CO)4 Fe(CO)3

Fe(CO)5

H7a H7a H7a

(8) (9) (10)

H7a Fe(CO)4 Fe(CO)3 H7a

H3a H3a H3a

-Fe(CO)4

H7a

(11) (12) Scheme 5 H3a H3a H3a

Fe(CO)2 Fe(co) 5

H7a OH7a OH 7a

(8) (13) (14)

Fe(CO)2 -Fe(CO)2

H3a

H3a H

OH 7a OH7a (16) (15)

H(H5a)

Fe(CO)2 H3a Scheme III H3a(H) H7a

OH7a (18) (17)

-Fe(CO)2

H(H3a)

H3a(H)

OH7a

H(H3a)

H3a(H)

H7a

(19)

6 Alternatively, as outlined in Scheme III, another possible mechanism involving a hydroxycyclopentadienyliron carbonyl complex (14) may also be operative. It is suggested that complex (14) is formed via the reaction of the enol

(13) of, (8) with iron pentacarbonyl a similar analogy of alkoxycyclopentadienyliron carbonyl complex has been reported.

Upon elimination of the metal, two possible isomeric.enols, viz, (15) and (16) may be generated. The keto form of (15) is the' 1-indanone (17), while (16) may undergo again the

formation of another hydroxycyclopentadienyliron carbonyl

complex (18) which subsequently leads to the formation of

the 1-indanone (19).

Although the two mechanisms described above give the

same end product, i.e. 1-indanone, the distribution of the

migrating hydrogens in the final product are not the same.

Thus by using deuterium labelling, some information about

the actual mode of the reaction may be obtained. Thus the

deuteriated compound (21) was synthesized starting from

cyclopentanone-2,2,.5, 5-d4 '(20) in accordance with the synthetic

pathways as outlined in Scheme IV. Cyclopentanone-2,2,.5,5-d4

(20) was in turn prepared according to the procedure9 as

describ.ed by Saunders Jr. using cyclopentanone and deuterium

oxide as starting materials.

Thus by treating (21) with iron pentacarbonyl and

Identifying the distribution of deuterium in the final product

1-indanone, a distinction can be made between the two proposed

mechanisms. Decarbonylation of (21) would initiallyield 7 D D D D Br Br NaOH HOCH2CH2OH D 2Br2 D D D D D H+ dioxane CH3OH

D D

D D spontaneous 70% H2SO4 D D D D D D

(21)

Scheme IV

the deuteriated compound (22). If the course of reaction follows

the mechanism as outlined in Scheme II, then l-indanone-2,3,4,7-d4

(24) is expected.

D D D

D D D D D

(22) (23) (24)

D Alternatively, if the mode of reaction follows the mechanism as outlined in Scheme III which involves keto-enol tautomerism and formation of hydroxycyclopentadienyliron carbonyl complexes,

both deuteriated 1-indanone (27) and (28) as described below are

expected. In fact, (28) is a mixture of (27) and (24).

D D D H

Fe(CO)2 D D D Fe(CO) 5 D OD OD D D D

(22) (25) ( 26 )

-Fe(CO)2 -Fe(CO)2 D D

H D D

OD D D OD

D D(H) D

Fe(CO)2

N(D) D

OD D D D (27)

D D(H)

H(D)

OD D

D D(H)

D H(D)

D 9(28) II. Reactions of the Ethylene Ketals of 3a, 4,7,7a-Tetrahydro-

4,7-methanoindene-1,8-dione (6) with Iron Pentacarbonyl:

In view of the fact that reaction of (6) with iron pentadarbonyl failed to yield the desired complex (7) but only afforded 1-indanone, the bisethylene ketal (5) was taken to react with iron pentacarbonyl in the hope that the complex

(29) is formed, The bisethylene ketal (5) has another advantage that it will not decarbonylate since there is no bridge carbonyl group in the molecule. If the synthesis of (29) were successful, hydrolysis of the two ethylene ketal groups would lead to the formation of the desired complex (7).

Fe(CO)5 H+

? ? Fe Fe CO CO CO CO CO CO

(5) (29) (7)

However, the ethylene ketal group in Cl-position may be too bulky and may hinder the attack.of the iron pentacarbonyl, and in. which case the'monoethylene ketal (30), obtained by partial hydrolysis of (5), would be a logical substitute. If the corresponding complex (31) were obtained, the remaining

10 ethylene ketal group would then be removed to afford (7)

Fe(CO) 5 H+

? ? Fe F co co CO co co co

(30) (31) (7)

III. Reactions of Other Carbonyl Bridged Compounds with Iron

Pen.tacarbonyl:

In connection with the finding of the reaction of 3a,k,7,7a-

tetrahydro-4, 7-methanoindene-l, 8-dione (6) with iron pentacarbonyl,

several analogous carbonyl bridged compounds have been synthesized

and their reactions! towards iron pentacarbonyl have been studied.

A. 2,4-Dibromo-3a,4,7,,7a-tetrahydro-4,7-methanoindene-l,8-dione

(32):

The dibromo derivative (32).has been synthesized'readily

by following Scheme V. By treating (32) with iron pentacarbonyl,

the formation of 2,4-dibromo--l-indanone (57) is expected, if

the presence of the bromine atoms will not affect the reaction

pathway as that studied for (6).

11 Br Br NaOH HOCH2CH2OH 3Br2 Br H dioxane CH3OH

Br Br Br

H2SO4

Br Br

(32)

Scheme V

B. 4,,5,6,7-Tetraphenyl-3a,4,7,7a-tetrahydro-4,7-methanoindene-

8-one (33):

The synthesis of (33) is outlined in Scheme VI and the choice for such compound is due to the fact that the carbonyl group in C3 position is absent and upon decarbonYlation 3a,7a- dihydroindene (34) would be obtained. Reaction of (34) with iron pentacarbonyl may lead to two possible products, viz, the

diene-iron tricarbonyl complex C357 and the rearranged compound

(36). Since a related diene-iron tricarbonyl complex (37) has

been reported10 and rearrangement of double bond is found for

12 (8), the chances for the formation of (35) and (36) are expected

to be equal. In addition, it is interesting to note that the presence of four phenyl groups in tetraphenylcyclopentadienone

(59) makes it to act as a Diels-Alder diene towards the reaction

with cyclopentadiene to form (33). In the absence of these

phenyl groups cyclopentadienone will act as a dienophile while

cyclopentadiene act as a usual diene, and 3a,4,7,7a-tetrahydro-

4,7-methanoindene-l-one (38) is formed.11

(33)

(59)

Scheme VI

13 CO CO CO-Fe

H ( 35)

Fe(CO) 5

(34)

(36)

CO CO CO -Fe

(37)

(38)

14 C. Octachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene-l, 8-dione

(39):

The octachloro derivative (39) was synthesized following the pathways as depicted in Scheme VII, and upon decarbonylation

(39) would lead to octachloro-3a,7a-dihydroindenone (40). As

there is no hydrogen atom in the underlining compound, it would

be of interest to know whether iron pentacarbonyl would catalyze

"l,3-chloroshift" in the same manner as the previous cases

for hydrogen shifts.

Scheme Ⅶ

40 41

15 RESULTS AND DISCUSSION

I. Reaction of.3a,4,7,7a-Tetrahydro-4,7-methanoindene-1,8-

dione (6) with Iron Pentacarbonyl:

3a,7a-Dihydroindenone (8) (see NMR-2 and IR-2a) was

obtained by the thermolysis of 3a,4,7,,7a-tetrahydro-4,7-methano-

1,,8-dione (6) (see NMR 1 and IR la) in xylene. under nitrogen

atmosphere. Treatment of (8) with a solution of excess iron

pentacarbonyl in refluxing xylene (12 hours) or dioxane (16

hours) afforded 1-indanone (see NMR-3 and IR-2b) in 670% or

56% yields, respectively. The corresponding iron carbonyl

complex (42) was not obtained. In addition, a mixture of (8),

iron pentacarbonyl and maleic anhydride was refluxed in a

similar fashion, and the adduct (43) (see NMR 4 and IR 3a)

was obtained in 80% yield, identical in every respect with

the product directly prepared from (8) and maleic anhydride

(91%). This result shows that the Diels-Alder reaction is

faster than the rearrangement of double bond from (8) to

1-indanone.

H Fe(CO)

-C0 H (8)

(6) Fe(CO)3 Fe(CO) 5 H

N 16(42) H

H Fe(CO)5

(4+3)

In a similar manner, treatment of (6) with excess iron pentacarbonyl in xylene for 16 hours gave 1-indanone in 53%

yield. There was no direct evidence to show that the decarbonyl-

ation did not involve the participation of iron pentacarbonyl.

However, the isolation of the adduct (43) (71%) from the

reaction in the presence of maleic anhydride indicates that

the transformation of (6) to l-indanone occurred stepwisely

via (8) as intermediate which underwent double bond migration.

Fe(CO)5

(6)

Fe(CO) 5

(43)

17 II. Mechanistic Studies:

Following the synthetic pathways outlined in Scheme IV, the deuteriated 3 a,4,7,7a-tetrahy.dro-4,7-methanoindene-l,8- dione (21) was obtained, with 70/ deuterium incorporation as

calculated from its N.M.R. spectrum (see NMR -5 and IR-lb).

By treating (21).with a solution of excess iron pentacarbonyl

in refluxing xylene under nitrogen atmosphere for-16 hours, the

reaction afforded the deuteriated 1-indanone (24) (see NMR-6).

The integrations of peak areas for the aromatic protons

and the aliphatic protons are equal this is expected for any

product, either (24) alone or a mixture of(27) and (24). However,

what is most significant is that the integrations of peak areas

for the two sets of aliphatic protons are also equal. Such

a spectrum would favour the deuteriated 1-indanone (24) which

was the product expected from the mechanistic pathway described

in Scheme II. Since the product(s) arising from the alternative

mechanism described in Scheme III would correspond to a mixture

including compound (27) the N.M.R. signals at the aliphatic

region would not appear as two equal sets. As a.result, a

possible mechanism involving two successive suprafacial 1,3-

hydrogen shifts is more likely. However, none of the intermediate

iron. carbonyl complexes has been isolated to establish the actual

mode of reaction.

D D D

ID ID T

. D .?-4) 27)

18 The iron pentacarbonyl catalyzed isomeriza tion of the alcohol (44) to the ketone (45) as reported by von Rosenberg and co-worker12 may bear some significance to the present study.

In spite of the smooth isomerization of (44) to (45), the epimeric alcohol (46) was unaffected. It was assumed that the iron atom

Interacted with the olefin on the same side as the bridge methylene

group of the molecule; hence the hydrogen which was on the same

side of the olefin as the attached iron atom was the one that has been migrated.

Fe(CO)5 Fe(CO)3

HO H HO

(44)

Fe(CO)5

H OH (46) (45)

Similarly, although none of the intermediate iron carbonyl

complexes have been isolated in the present work, it is no

unreasonable to propose a possible structure for the intermediate

(olefin)-Fe(CO)4 complex (9) as illustrated below. The significance

19 of (9) is that the iron atom lies on the same side of the migrating hydrogen atoms.

Ha H Fe(.CO)

Concertedly,, thermally induced, (1,3)-sigmatropic hydrogen

shifts are allowed", according to the Woodward and Hoffmann

rules,7 to proceed only via the sterically unfavourably antara-

facial mode, and it is significant that no such migrations have

been reported. However, 1,3-hydrogen shifts brought about by

the influence of a metal catalyst could conceivably occur

through the sterically favourable suprafacial pathway. An

explanation for such contradictory behavior has been given by

Pettit,13 and Mango and Schachtschnei der.l4 In essence,it is

concluded that interaction of appropiate metal orbitals with

those of the olefin forms a new set of occupied molecular

orbitals which provide a symmetry allowed reaction pathway.

The present work may be of general interest because it

describes the first example of the iron pentacarbonyl promoted

rearrangement of 5-alkenylcyclohexadiene system to benzenoid

derivative--which is 1-indanone in this particular case. The

fact that 3a,7a-dihydroindene afforded a stable iron carbonyl

complex (37) without double bond migration 10 and 3a,7a-dihydro-

20 indenone (8) only resulted rearrangement in good yield is striking. Along this line, 5-vinylcyclohexadienes,.15 3a,.7a- dihydrobenzofuran,16 and 2a,6a-dihydrobenzocyclobutadienel7 all afforded the corresponding diene-iron tricarbonyl complexes

(47) (48), and (49), respectively,, also without the movement

of double bonds to give benzenoid derivatives.

Fe(CO) 5

(8)

H H Fe (CO)3 Fe(CO)5

H H (37)

R Fe(CO)3 R H H Fe(CO) 9 R R

R R

(47)

R Fe(CO)3 H H R Fe(CO) 5

R R

H H

(48)

Fe(CO)3 H H Fe(CO)5

H H (49) 21 Reactions of conjugated dienes with iron pentacarbonyl always lead to the formation of iron pentacarbonyl complexes.3

These complexes are usually very stable and the bond energy may sometimes even offset the stablization energy of the aromatic ring. For instance, vinylbenzene18 and 1,4-divinyl-

benzene19 afforded the corresponding iron carbonyl complexes

(50) and (51), respectively. In such systems, the aromaticity

were destroyed as evidenced by X-ray crystallography which

showed significant differences in carbon-carbon bond lenghts

in the benzene moiety.

Fe(CO).

Fe(CO) 5

(50)

- Fe(CO)3

Fe(CO)5

-Fe(CO)3

51)

Furthermore, the stable iron carbonyl complex (52) of

"o,p'-dibenzene (53) has recently been reported.20 The

stability of (52) over the aromatic stability by two benzene

rings is worth-mentioning. 22 Fe(CO)

52)

Ce4+ Rapid. (52) 2

(53)

In contrast, the present work showed that iron pentacarbonyl catalyzed the formation of the aromatic 1-i.rdanone rather than affording the iron carbonyl complex (42). Such contradictory phenomenon was unclear.

III. Reactions of the Ethylene Ketals of 3a,4,7,7a-Tetrahydro-

4,7-methanoindene-l,8-dione (6) with Iron Pentacarbonyl:

After a solution of 3a,4,,7,7a-tetrahydro-4,7-methanoindene-

1,8-dione bisethylene ketal (5) (see NMR 7) and iron pentacarbonyl

in xylene had been refluxed under nitrogen atmosphere for 24

hours, only the starting material (84%) was recovered from the

reaction mixture. No corresponding iron carbonyl complex (29)

was obtained. It was then thought that the ethylene ketal group 1 in C1 position may be too bulky and may hinder the attack of

23 iron pentacarbonyl. However, similar treatment of 3a,4,7,7a-

tetrahydro-4,7-methanoindene-l,8-dione 8-ethylene ketal (30)

(see NMR-8) with iron pentacarb.onyl only again resulted in

the isolation of the starting material (78%). The unsuccessful

preparation of the corresponding iron carbonyl complex (31) may be

offered in terms of the fact that the atomic size21 of iron

atom (1.26 A) is not large enough to overlap with the orbitals

of the underlining diolefin. In contrast, the atomic size21

of platinum atom (1-38A) may be large enough to form the

corresponding platinum complex (1) which has been reported.1

Besides, the carbonyl group in C1 position of (30)may also be

another determining factor in complex formation. However, the

actual situation was unclear.

Fe(CO) 5

Fe OC CO CO

(5) (29)

Fe(CO)5

OC Fe CO CO

(30) (31) 24 IV. Reactions of Other Carbonyl Bridged Compounds with Iron

Pentacarbonyl:

A. 2,4-Dibromo-3a,4,7,7a-tetrahydro-4,7-methanoindene-l,8-

dione (32):

2,,4-Dibromo-3a,, 7a-dihydroindenone (54) (see NMR 10 and

IR-4a) was obtained by thermolysis of 2,4-dibromo-3a,4,7,7a-

tetrahydro-4,7-methanoindene-l,8-dione (32) (see NMR-9) in

xylene.under nitrogen atmosphere and its structural assignment

was supported by satisfactory spectroscopic data. Treatment

of (54) with a solution of excess iron pentacarbonyl in refluxing

xylen'e (8 hours) or dioxane (12 hours) afforded 4-bromo-l-indanon,

(55) (see NMR 11 and IR 4c) in 38% or 36% yields, respectively.

Again, the corresponding iron carbonyl complex (56) was not

obtained. Furthermore,the expected rearrangement product,

2,4-dibromo-l-irldanone (57) (see NMI ---12 and IR 4.b) was not

detected.

Br Br Br H A, Fe(CO)5 Br -Co

H Br (54)

(32) (55)

Br (O) P H

(56)

25 A mixture of (54), iron pentacarbonyl and maleic anhydride was refluxed in a similar manner, and the adduct (58) (see NMR-

13 and IR-3b) was obtained in 8b% yield, identical in every

respect with that directly prepared from (54) and maleic anhydride

(88/). Since the bromine atom at C2 position of (58) is unaffected

by iron pentacarbonyl, this result showed not only that the

Diels-Alder reaction was faster than any other reactions that

occurred but also the possible reaction sequence was in the

order of rearrangement of double bond from (54) to (57) then

followed by debromination of (57) to (55).

Br Br i H Fe(CO) 5

Br Br

(54) 58)

Br B1 Br H

Fe(CO) 5 Fe(CO) c Br Br

(54) (57) (55)

In a similar fashion, treatment of (32) with iron penta-

carbonyl in xylene gave 4-bromo-l-indanone (55) in 33% yield.

Again, no direct evidence showed that the decarbonylation did

not involve the participation of iron pentacarbonyl. However,

26 the isolation of the adduct (58) (70%) from the reaction mixture in the presence of maleic anhydride indicated that the trans-

formation of (32) to (55) occurred via (54) as intermediate which underwent double bond migration and subsequent debromination.

Fe(CO)5

Br (55)

Br Br

(32) Br

Fe(CO)5

(58)

Apart from the migration of double bond observed in this

system, which behaved in similar fashion as (8) and has been

discussed, the subsequent debromination is also note-worthy.

Recently, Alper and Keung22 reported that iron pentacarbonyl

reacted with a variety of a- halo ketones in refluxing 1,2-

dimethoxyethane, which upon treatment with water, generally

gave the coupled 1,4-diketones and reduced monoketones. They

also claimed that use of deuterium oxide instead of water resulted

in c-deuteri.oketone formation.. On the other hand, if the reaction

mixture was not poured into water, no reduced monoketone was

obtained. Therefore, they concluded that the hydrogen for the

reduced monoketone was derived from water and not from the solvent,

1,2-dimethoxyethane.

27 In the present work, xylene. was employed as solvent, and the reaction and work-up conditions were strictly anhydrous.

The isolation of the reduced mon.oketone (55), which was contrary

to the results of Alper and Keung,22 is worthy of further investigation.

B. 4, 5,6, 7-Tetraphenyl-3a,.4, 7, 7a-tetrahydro-4,7-methanoindene-

8-one (33):

In order to expel the bridge carbonyl group of (33) (see

NMR-l4) as carbon monoxide to form 4,5,6,7-tetraphenyl-3a,7a-

dihydroindene (34), (33) in xylene was allowed to reflux under

nitrogen atmosphere for 5 hours. Column chromatography of the

cooled reaction mixture resulted in the isolation of dicyclopenta-

diene and tetraphenylcyclopentadienone (59) (see NMR-15). No

decarbonylated product (34) was obtained.

-co

(34)

(33) (59)

r. t.

28 To prevent dissociation of (33) in retro-Diels-Alder manner, dioxane which has a lower boiling point than xylene

was used as solvent, However, only starting material (33)

(98%) was recovered after refluxing for 10 hours.

The reaction. of (33) with iron pentacarbonyl in xylene

afforded two iron carbonyl complexes, viz, tetraphenylcyclo-

pentadienone-iron tricarbonyl (60) (see IR 5) and dicyclo-

pentadienyldi-iron tetracarbonyl (4) (see IR-6). The isolation

of (60) and (i) were apparently arised from the fact that the

dissociation of (33) gave tetraphenylcyclopentadienone (59)

and cyclopentadiene, which in turn reacted with iron penta

carbonyl individually to afford (60) and (4).

(60)

Fe(CO).3

Fe(CO) 5

(33) Co Co

Fe ------Fe (4) I 1

oc co

29 C. Octachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene-1,8-

dione (39):

Octachloro-3a, 7a-dihydroindenone (40) (see IR 7b) was

obtained by the thermolysis of (39) (see IR--7a) in xylene

under nitrogen atmosphere. Treatment of (40) with a solution'

of excess iron pentacarbonyl in refluxing xylene afforded

hexachloroindenone (61) (see IR-7c). Corresponding iron

carbonyl complex (62) and rearrangement product (41) were not

obtained. In addition,, an attempt to synthesize the corresponding

Diels-Alder adduct (63) of (40) and maleic anhydride was

unsuccessful..

Cl I Cl Cl Cl Cl Cl Cl C C1 Fecco)5 (4l)

Cl Cl Cl Cl Cl Cl C1 Cl Cl Cl -Co Fe (CO)s Cl Cl C -Cl Cl -Cl Cl Cl Cl Cl I Cl Cl

(61) (39) (40)

r r CJ` Cl I Cl Cl Cl A. Y Fe J6v -c l (CO)3cl

Il Cl

(62)

30 Cl Cl Cl Cl Cl Cl C1 Cl Cl Cl Cl Cl Cl Cl C1 Cl

(40) (63)

In a similar manner, treatment of (39) with iron penta-

carbonyl also gave hexachloroindenone (61). However, the role

that iron pentacarbonyl played in such reaction was not established.

Besides, the same product (61) was also obtained when (39)

was heated with water, as previously reported.35

Cl Cl Cl Cl Cl Fe(CO)5 Cl Cl Cl Cl Cl Cl Cl Cl

(39) (61)

31 EXPERIMENTAL

All melting points were determined with a Kofler micro- heating stage and are reported uncorrected. Infrared spectra were recorded on a Beckman IR-l0 spectrophotometer or a Perkin-

Elmer 283 infrared spectrophotometer. Proton magnetic resonance spectra were recorded on a JOEL 60 HL spectrometer using tetra- methylsilane as the internal standard. Mass spectra were measured with a Hitachi RMS-4 spectrometer. Microanalyses were

performed by the Australian Microanalytical Service, Melbourne

University, Victoria, Australia. Iron Pentacarbonyl (E. Merck)

was used without further purification. Solvents were purified by standard methods. 23

Cyclopentanone Ethylene Ketal

A mixture of cyclopentanone (252 g, 3.0 mol), benzene

(1.0 1), and p-toluenesulfonic acid monohydrate (0.2 g) was

placed in.a 2-1. two-necked flask equipped with a 150-m1

addition funnel and a Dean Stark water separator. The solution

was heated under reflux and ethylene glycol (200 g, 3.2 mol)

was added slowly from the dropping funnel over a period of one

hour. After 5 hour of reflux, when water separation was complete

(54 ml collected), the reaction mixture was cooled, washed twice

with 2N NaOH solution and once with water. The organic solution

was then dried over anhydrous magnesium sulfate, filtered, 32 and distilled to give cyclopentanone ethylene ketal (285 g,

74%), b.p. 154-156°C (lit.,24 152-155°C), with satisfactory n. m. r. and i.r. spectra.

2,5-Dibromocyclopentanone Ethylene Ketal

Cyclopentanone ethylene ketal (64 g, 0.5 mol) in pure dioxane (500 ml) was cooled to 10-15°C under a dry atmosphere.

Bromine (160 g, 1.0 mol) was added dropwise with stirring

during 2 h, keeping the mixture below 15°C.. After bromine

had been added, the mixture was allowed to attain room temperature

and then stirred for a further hour. The mixture was then poured

into 51% aqueous sodium bicarbonate (2.5 1) and extracted with

ether (3x250 ml). The combined ethereal solution was washed

with water and dried over anhydrous magnesium sulfate. Evaporation

of the ether in yacuo gave a brown oil which usually solidified

when kept in the refrigerator overnight. Recrystallization

from ethanol afforded 2,5-dibromocyclopentanone ethylene ketal

(74 g, 52%), m. p. 60-62°C (lit. 24 62-64°C), with satisfactory

n.m.r. and i.r. spectra.

3a, 4,7,7a-Tetrahydro-4, 7-methanoindene 1, 8 dione Bisethylene

Ketal (5)

2,5-Dibromocyclopentanone ethylene ketal (128 g, 0.45 mol)

was mixed with methanol solution (400 ml) containing sodium

hydroxide (80 g) and allowed to reflux for 5 h. The mixture

was then cooled, poured into saturated NaCl solution (600 ml),

33 and extracted with methylene chlboride (3x250 ml). The combined extract was washed with water, dried over anhydrous magnesium

sulfate, and evaporated in vacuo. The brown solid obtained

was dissolved in hot ethanol and treated with decorlorizing

charcoal. Upon standing brilliant white sheet-like crystals of

3a,4,7,7a-tetrahydro-4,7-methanoindene-l,8-dione bisethylene

ketal (5) was obtained:(31 g, 56%), m.p. 90-92°C (lit.,24 91-

92°C), &(CDC1) 3 2.61-3.02.(3 H, m, H-3a, 4 and 7), 3.40-3.78

(1 H, m, H-7a), 3.85-4.02 (8 H. m, two OCH2CH2O) 3 5.54-5.98

(3 H, MI H-2,.5 and 6), and 6.12-6..31 (1 H, m,' H-3).

3a5,4,.7,7a-Tetrahydro-4,,7-methanoindene-1, 8-ddione 8-Ethylene

Ketal (30)

Concentrated hydrochloric acid (5 ml) was added dropwise

at room temperature to a stirred solution of compound (5) (4 g,

0.016 mol) in tetrahydrofuran (50 ml). The mixture was stirred

overnight,, poured into 10% aqueous sodium bicarbonate (300 ml),

and kept at room temperature. for one hour. The precipitate

thus formed was filtered and recrystallized from ethanol to

give 3a,,4,,7,7a-tetrahydro-4,7-methanoindene-l,8-dione-8-ethylene

ketal (30) (2.5 g, 77%), m.p. 93-94°C (lit.,25 95-95°C), & (CDC1)3

2.80-3.12 (3 H,. m, H-3a, 4 and 7), 3.38-3.80 (1 H, m, H-7a),

3.85-4.10 (4 H, m,, OCH2CH2O), 5.75-6.28 (3 H, m, H-2, 5 and 6),

7.38 (1 H, dd, J 7 and 3 Hz, H-3)

3a,4,7,7a-Tetrahydro-4,7-methanoindene-l,8-dione (6)

A solution or compouna (5) 13.5. g, 05 mol) in 70%

34 sulfuric acid (100 ml) was stirred at room temperature for ca.

24 h. The reaction mixture was then poured onto crushed ice

(100 g) and the aqueous mixture was extracted with methylene chloride (2x200 ml). The combined extract-was then washed with water, dried over anhydrous magnesium sulfate, and evaporated in vacuo. The.solid residue was recrystallized from ethanol

to give 3a,14.,7,7a-tetrahydro-4,7-methanoindene-1,8-dione (6)

(7.0 g, 81%), m.p. 99-100°C (lit.,6 99-99.5°C), v max (KBr) 1775

(bridge C.0), 1701 (C=O), and 1581 cm-1 (C=C) S (CDC13) 2.90

(1 H) t, J 5.8 Hz, H-7a), 3.02-3.68 (3 H, m) H-3a, 4 and 7),

6.04-6-46 (3 H, m, H-2,5 and 6), and 7.40 (1 H, dd) J 6 and

2.5 Hz, H-3).

3a,7a-Dihydroindenone (8)

3a,4, 7, 7a-Tetrahydro-4, 7-methanoindene-l, 8-dione (6) (5.2 g,

0.0325 mol) in xylene (200 ml) was refluxed.under nitrogen

atmosphere for ca. 5 h.- The. solvent was then removed

in vacuo and the yellowish liquid was distilled to give colorless

liquid of 3a,7a-dihydroindenone (8) (2.7 g, 63%), b. p. 86-

88°C at 0.15 mmHg (lit.,26 120-125°C at 1 mmHg),Vmax .(NaCl)

1702 (C=0) and 1582 cm (C=C) 3(CDC1 3) 3.10-3.40 (1 if, m, H-7a),

3.58-3.92 (1 H, m, H-3a), 5.40-5.88 (4 H, m, H-4, 5, 6 and 7),

6.27 (1 H, dd:, J 6 and 2.5 Hz, H-2), and 7.55 (1 H, dd, J 6 and

2.5 Hz, H-3).

1-Indanone

3a,7a-Dihyaroinaenone (8) (1 g, 0.0075 mol) was dissolved in 35 glacial acetic acid (25 ml) to which dry hydrogen chloride gas was passed for ca. 5 min. The mixture was then stirred at room temperature for ca. 24 h, poured into ice cold water, and the aqueous mixture was extracted with ether (2x75 ml). The combined

ethereal solution was dried over anhydrous magnesium sulfate and evaporated in vacuo. The solid residue obtained was recrystallized

from ethanol to afford colorless sheet-like crystals of 1-indanone 27 (0.52 g, 52%) m. p. 40-41°C (lit.,27 40-41°C), max (KBr) 1700

cm -1 (C=O) (CDCl3) 2.50-2.78 (2 H, m, CH2CO), 2.96-3.25 (2 H)

m, CH2Ar), and 7.16-7.86 (4 H, m, Ar).

Adduct(43) of 3a, 7a-Dihydroindenone with Maleic Anhydride

A mixture of 3a, 7a-dihydroindenone (8) (1.32 g, 0.01 mol)

and maleic anhydride (0.98 g, 0.01 mol) in benzene (50 ml) was

stirred at room temperature for 2 h. The white solid thus forged

was filtered and recrystallized from acetone to give the

corresponding adduct (43) (2.1 g 91%), m.p. 244-245°C (lit.,28 243-

244°C), max (KBr) 1848 and 1770 (C=O, anhydride), 1684 (C=O), and

1582 cm-1 (C=C) (CD3 COCD3) 2.55-2.85 (1 H, m, CHCOC=C), 3.20

3.80 (5 H,. M. CHC=CCO, CH-(bridge C=C)-CH, and 2 CHCO0), 5.90-

6.30 (3 H, m, COCHC=C, and bridge CH=CH), and 7.60-7.78 (1 H,

m, COC=CH) m/e 230 (M+).

Reaction of 3a,4,7,7a-Tetrahydro-4,7-methanoindene-1,8-dione

Bisethylene Ketal (5) with Iron Pentacarbonvl

A solution of (5) (2.5 g 0.01 mol) and iron pentacarbonyl 36 (4.0 g, 0.02 mol) in xylene (150 ml) was refluxed under nitrogen atmosphere for ca. 24 h. The reaction mixture was cooled,

filtered, and the solvent removed in vacuo. The residue obtained was found to be the starting material (5) (2.1 g, 84%).

Reaction of 3a, 4, 7, 7a-Tetrahydro-4, 7-methanoindene-l, 8-dion.e

8-Ethylene Ketal (30) with Iron Pentacarbonvl

A mixture of (30) (1.8 g, 0.0088 mol) and iron pentacarbonyl

(3.4 g, 0.0173 mol) in xylen e (150 ml) was refluxed under

nitrogen. atmosphere for ca. 24 h. The reaction mixture was

then cooled,, filtered, and the solvent evaporated in vacuo.

The residue obtained was found to be the starting material (30)

(1.4 g, 78%).

Reaction of 3a, 4,7,7a-Tetrahydro-4, 7-methanoindene-1, 8-dione

(6) with Iron.Pentacarbonyl

A mixture of (6) (4.2 g, 0.0263 mol) and iron pentacarbcnyl

(10.3 g,, 0.0526 mol) in xylene (200 ml) was re fluxed under

nitrogen atmosphere for ca. 16 h. The reaction mixture was

then cooled, filtered and the solvent evaporated in vacuo. The

solid residue obtained was recrystallized from ethanol to afford

1-indanone (1.85 g, 53%), which-was identical in all respects

(mixed m. p., i.r. and n. m. r. spectra) with an authentic sample.

Reaction of 3a,7a-Dihydroindenone (8) with Iron Pentacarbonyl

A mixture of (8) (1.5 g, 0.0114 mol) and iron pentacarbonyl

(4.5 g, 0.023 mol) in xylene (100 ml) was refluxed under

39 nitrogen atmosphere for ca. 12 h. The reaction mixture was then cooled, filtered and the solvent removed in vacuo. The

solid residue obtained was recrystallized from ethanol to

give 1-indanone (1.0 g, 67%), which was identical in all respects

(mixed m. p., i.r. and n. m. r. spectra) with an authentic sample..

RPactin of (6) with Iron Pentacarbonyl in the Presence of

Maleic anhydride

A mixture of (6) (0.8 g, 0.005 mol), iron pentacarbonyl

(2.0 g, 0.01 mol),, and maleic anhydride (0.5 g,. 0.005 mol)

in xylene(75 ml) was allowed to reflux under nitrogen

atmosphere for ca. 16 h. The reaction mixture was then cooled,

filtered, and the residue was washed with hot acetone.

The combined filtrate was evaporated in vacuo. The solid

obtained was recrystallized from acetone to give the adduct

(43) (0.82 g, 71%), which was identical in all respects (mixed

m.. p., i. r. and n. m. r. spectra) with an authentic sample. No

1-indanone was obtained in addition to the adduct.

Reaction of (8) with Iron Pentacarbonyl in the Presence of

Maleic Anhydride

A mixture of (8) (0.66 g, 0.005 mol), iron pentacarbonyl

(2 g, 0.01 mol), and maleic anhydride (0.5'g, 0.005 mol) in

xylene (75 ml) was allowed to reflux under nitrogen atmosphere

for ca. 12 h. The reaction mixture was cooled, filtered, and

the residue was washed with hot acetone. The combined solution

was then evaporated in vacuo to afford a solid residue. Upon 38 recrystallization. from acetone gage the adduct (43) (0.93 g,

80%), which was identical in all respects (mixed m.p.,i.r. and n. m. r. spectra) with an authentic.sample. No 1-indanone was obtained in addition to the adduct.

2,2,5-Tribromocyclopentanone Ethylene Ketal

Cyclopentanone ethylene ketal (128 g, 1.0 mol) in pure

dioxane (1.0 1) was cooled to 10-15°C under a dry atmosphere.

Bromine (480 g, 3.0 mol) was added dropwise with stirring

during 2.5 h, keeping the mixture below 15°C. After bromine

had-been added, the mixture was allowed to attain room temperature

and. then stirred overnight. The reaction mixture was then

poured into 10% aqueous sodium bicarbonate (3 1.) and stirred

for an hour. The aqueous mixture was extracted with methylene

chloride (3x500 ml). The combined organic solution was

washed with water and dried over anhydrous magnesium sulfate.

Evaporation of the solvent in vacuo afforded a brown oil, which

usually solidfied when kept in refrigerator overnight.

Recrystallization from ethanol gave 2,2,5-tribromocyclopentanone

ethylene ketal (220 g, 60%)3 m.p. 74-76°C (lit., 24 76-78°C),

with satisfactory n.m.r. and i.r. spectra.

2,4-Dibromo-3a,4,7,7a-tetrahydro-4,7-methanoindene-1,8-dione

Bisethylene Ketal

2,2,5-Tribromocyclopentanone ethylene ketal (150 g, 0.4)

mol) was mixed with a methanol solution (400•m1) containing sodium hydroxide(80 g). The39 mixture was allowed to reflux for 5 h, poured into saturated NaCl solution (600 ml), and

the aqueous mixture was extracted with methylene chloride

(3x2 50 ml). The combined extract was washed with water,

dried over anhydrous magnesium sulfate, and evaporated in

vacuo. The solid obtained was recrystallized from ethanol

to give 2,4-dibromo-3a,4,,7,,7a-tetrahydro-4,7-methanoindene-

l,8-dione bisethylene ketal(41 g,49%),m.p. 172-174°C (lit., 24

172-174°C), with satisfactory n.m.r. and i.r. spectra.

2, 4 Dibromo-3a,4,7,7a-tetrahydro-4, 7-methanoindene-1, 8-dione

8-Ethylene Ketal

Concentrated hydrochloric acid (50 ml) was added

dropwise at room temperature to a stirred solution of

2,4-dibromo-3a,4,7,7a-tetrahydro-4,7-methanoindene-l,8-dione

bisethylene ketal (50 g, 0.123 mol) in tetrahydrofuran (500 ml).

The.mixture was allowed to stir overnight, poured into 10%

aqueous sodium bicarbonate (3.0 1), and then kept at room

temperature for one hour. The solid thus formed was filtered,

dried in vacuo, and recrystallized from ethanol to give

2,,4-dibromo-3a, 4, 7, 7a-tetrahydro-4, 7-methanoindene-l,8-dione

8-ethylene ketal (34 g, 76%), m. p. 170-172°C (lit., 24 171-172),

with satisfactory n.m.r. and i.:r. spectra.

2,,4-Dibromo-3a,4,7,7a-tetrahydro-4,7-methanoindene-1,8-dione (32)

A solution of 2,4-dibromo-3a,4,,7,7a-tetrahydro-4.,7-

methanoindene-l,8-dione bisethylene ketal (20 g, 0.055 mol)

in concentrated sulfuric acid (100 ml) was stirred at room

temperature for ca. 36 h. The mixture was poured onto crushed

40 ice and the aqueous mixture was-extracted with methylene chloride (2x250 ml). The combined extract was then washed with water, dried over anhydrous magnesium sulfate,, and

evaporated in vacuo. The solid residue obtained was dissolved

in hot carbon tetrachloride and treated with decolorizing

charcoal. Upon crystallization from the cold solution afforded

fine white needles of 2,.4-dibromo-34,4,7,za-tetrahydro-4,7-

methanoindene-l,8-dione (32) (12.9 g,74%,. m. p. 154-155°C dec

(lit. 24 154-155°C dec), v max (KBr) Br) 1792( bridge C=0), 1710

' (C=O), and 1582 cm-1 (C=C) 8(CDC13) 3.06-3.26 (1 H, m, H-7a),

3.40-3.66 (2 B, m, H-3a and 7), 6.10-6.45 (2 H,, m, H-5 and 6),

and 7.62 (1 H, d, J 3 Hz, H-3).

2,4-Dibromo-3a,7a-dihydroindenone (54)

Compound (32) (4.5 g, 0.0142 mol) in xylene (200 ml)

was allowed to reflux under nitrogen atmosphere for ca. 7 h.

The mixture was cooled and the solvent was removed in vacuo.

The oily residue was then placed irn a refrigerator for one

week to give a yellow solid. Recrystallization from 'a

mixture of benzene and pentane afforded' 2,4-dibromo-3a,7a-

dihydroindenone (54) (3.2 g, 78%), m. p. 43-45oc (Found: C,

37.56 H, 2.32. C9H6OBr2 requires C, 37.28 H, 2.09%) Vmax

(KBr) 1720 (C=0) and 1598 cm-1 (C=C) (Ccl 1+) 3.54 (1 H, m,

H-7a),. 3.94 (1 H, m, H-3a), 5.62(2 H, m, H-6 and 7), 6.18

(L H. m, H-5), and 7.82 (1 H, d) J 3 Hz, H-3); m/e 288 (M+),

290 (M++2), and 292 (M++4).

41 2,4-1 Dibromo-1-1ndanone 57)

Compound (54) (0.7 g, 0.0024 mol) was dissolved in glacial

acetic acid (20 ml) to which dry hydrogen chloride gas was

passed for ca. 5 min. The mixture was stirred at room temperature

.for ca. 24 h, poured into ice cold water, and the aqueous mixture

was extracted with ether (2x50 ml). The combined ethereal

solution was washed with water and dried over anhydrous magnesium

sulfate. The solvent was then removed in vacuo and the residue

obtained was recrystallized from ethanol to afford 2,4-dibromo-

1-indanone (57) (0.4 g, 57%), m.p. 80-82°C (lit., 24 80-

82°C)max (KBr) 1728 cm-1 (C=O) & (CC 1 )'3,06-4-02 (2 H, m,

COCBrCH2),, 4.45-4.66 (1 H, dd, J 7 and 4 Hz, H-2), 7.20-7.50

(l H, m, H-7), and 7.68-7.94 (2 H, m, H-5 and 6).

Adduct (58) of 274-Dibromo--3a, 7a-dihydroindenone with Maleic

Anhydride

A mixture of compound (54) (0.5 g, 0.0017 mol) and maleic

anhydride (0.17 g, 0.0017 mol) in xylene (30 ml) was stirred

at room temperature for 4 h. The solid thus formed was filtered

and recrystallized from ethanol to afford the 2,4-dibromo-3a,7a-

dihydroindenone maleic anhydride adduct (58) (0.59 g, 88%), m. p.

292-29400 (Found: C, 40.45 H, 2.25 Br, 41._00. C13 H8+ 04Br 2 requires

C, 40.24 H, 2.08 Br,' 41.19%) V max (KBr) 1858 and 1781 (C=05

anhydride), 1710 (C=O), and 1587 cm-1(C=C) 8(CD 3 COCD 3 )3e12-3v46

(1 H, m, CHCOCBr=C), 3.40-3.80 (2 H, m, CHC=CBrCO and CH-(

bridge C=C) -CBr), 3.88-3.98 (2 H, m, 2 CHCO0) 3 6.06-6.20 (2 H,

m, bridge CH-CH), and 7.95 (1 H, d, J 4 H z5 COCBr=CH) m/e

386 (M+), 388 (M++2), and 390 (M++4). 42 Reaction of 2,4-Dibromo-3a,4,7,7a-tetrahydro-4,7-methanoindene-1, 8-dione (32) with Iron Pentacarbonyl

A mixture of (32) (0.52 g, 0.0016 mol) and iron penta-

carbonyl (0.64 g, 0.0033 mol) in xylene (75 ml) was refluxed under nitrogen atmosphere for ca. 12 h. The reaction mixture

was cooled, filtered and the solvent was removed in vacuo.

The residue obtained was recrystallized from cyclohexane to

give 4-bromo-l-indanone (55) (0.11 g, 33%), m.p. 93-94°C (lit., 29

94-95°C), max (KBr) 1710 cm-1 (C=0) 8(CC14) 2,48-2.80.(2 H)

m, COCH2), 2.84-3.22 (2 H, m, CH2Ar), 7.06-7.44( 1 H, m, H-7),

and 7.52-7.82 (2 H, m, H-5 and 6).

Reaction of 2,4-Dibromo-3a,7a-dihydroindenone (54) with Iron

Pentacarbonyl

2,4--Dibromo-3a,7a-dihydroindenone (54) (0.7 g, 0.0024 mol)

was mixed with iron pentacarbonyl (1.0 g,. 0.0051 mol) and

allowed to reflux in xylene (75 ml) under nitrogen atmosphere

for ca. 8 h. The reaction mixture was cooled, filtered, and

the solvent was removed in vacuo. The solid residue obtained

was recrystallized from cyclohexane to give 4-bromo-l-indanone

(55) (0.19 g, 38%), m.p. 93-94°C, which was identical with

the product obtained above from reaction of (32) with iron

pentacarbonyl.

Reaction of (32) with Iron Pentacarbonyl in the Presence of

Maleic Anhydride

A mixture of compound (32) (0.3 g, 0.00094 mol), iron 43 pentacarbonyl (0.36 g, 0.00188 mol) and maleic anhydride

(0.1 g, 0.00 102 mol) in xylene (50 ml) was re fluxed under nitrogen atmosphere for ca. 12 h. The reaction mixture was

cooled, filtered and the residue was washed with hot ethanol.

The combined filtrate was evaporated in vacuo to afford a

solid residue. Recrystallization from ethanol gave the adduct

(58) (0,25 g, 70%), which was identical in all respects (mixed

m. p., i. r. .and n. m. r spectra) with an authentic sample.

Neither 2,4 -dibromo--l--indanone nor k-brorno-l--indanone 1,was

obtained in addition to the adduct.

reaction of 2,4 -dibromo-3a,7a-dihydroindenone(54)with Iron) win iron

Pentacarbonl in the Presence of Maleic Anhydride

A mixture of compound (54) (0.35 g, 0.0012 mol), iron

pentacarbonyl (0.47 g, 0.0024 mol) and maleic anhydride (0.12 g,

0.0012 mol) in xyl ene (50 m.l) was allowed to re flux under

nitrogen for ca. 8 h. The reaction mixture was cooled, filtered,

and the residue was washed with hot ethanol. The combined

filtrate was evaporated in vacuo to give a solid residue,

Recrystallization from ethanol afforded the adduct (58)

(0.38 g, 80%), which was identical in all respects (mixed m.p.,

i.r. and n,m.r. spectra) with an authentic sample. Neither

2,4-dibromo-l-indanone nor 4-bromo-l-indanone was obtained

in addition to the adduct.

Tetraphenylcyclo-oentadienor.c (59) Benzil ('21 g, 0.1 mol)44 and 1, 3-dipheny lacetone (21. g, 0.1 mol) were dissolved in hot-ethanol (150 ml) and placed

in a 250--mlround-bottomed flask fitted with a reflex condenser.

The temperature of the solution was raised slowly to boiling,

and a solution of potassium hydroxide (3 g) in ethanol (15 ml)

was added slowly in two portions through the head'of the condenser.'

When frothing had subsided the mixture was refluxed for 15 min.,

and then cooled to 0°C, The dark purple crystalline solid was

filtered with suction and washed with 95% ethanol (3x10 ml)

to give tetraphenylcyclopentadienone:(59) (28 g, 73%), m. p. 218-290°C

(lit,,30 218-2200C), with satisfactory n.m.r. and i.r. spectra.

4 7, b, 7--L'etrapnenyl-- a, 4,(, a tetranyaro-4,' -met!zanoind.ene

8-one (33)

A mixture of tetraphenylcyclopentadienone (59) (23 g, 0.06 mol)

and freshly prepared cyclopentadiene31 (10 ml) in benzene (70 ml)

was re fluxed for 4h. The mixture was cooled, diluted with

petroleum ether (60-80°C) (140 ml) and allowed 'to stand overnight

in the refrigerator. The pink crystalline mass was filtered

with suction, washed with petroleum, ether (60-80°C) and after

drying in air gave 4,5,6,7-tetraphenyl-3a,4,7,7a-tetrahydro-4,7-

methanoindene-8-one (33) (13.4 g, 47%), m. p. 188-190°C dec

(lit.,32 188-190°C dec), with satisfactory n.m.r. and i.r. spectra.

Attempted Decarbonylation o f 4, 5, 6, 7-`retraphenyl-3a, 4, 7, 7a-

tetrahyd-ro-4, 7-methanoindene-8--one (33)

Compound (33) (1 g, 0.0022 mcl) in xylene (50 ml) was

45 allowed to reflux under nitrogen atmosphere for ca. 5 h. The mixture was cooled and the solvent was removed in vacuo. The residue was chromatographed on neutral alumina column using benzene as eluent. Dicyclopentadiene (0.12 g, 83%) was eluted followed by tetraphenylcyclopentadienone (59) (0.7 g, 84%).

No decarbonylated compound (34) was detected.

In a similar reaction, compound (33) was refluxed in dioxane

for ca. 10,h. and only starting material (33) (98) was recovered.

Reaction of 4,5,6,7-Tetrapnenyl-3a,4,7a-tetranyaro-4,7-metnano-

indene-8-one with Iron. Pentacarbonyl

A mixture of compound (33) (0.31 g, 0.0007 mol) and iron

pentacarbonyl (0.27 g, 0.0014 mol) in xylene (50 ml) was refluxed

under nitrogen atmosphere for ca.5 h. The mixture was cooled,

filtered, and the residue was washed with pure acetone. The

combined filtrate was evaporated in vacuo and the residue was

chromatographed on neutral alumina column. DicycloDentadiene

(0.01 g, 22%), tetraphenylcyclopentadienone (59) (0.05 g, 18%),

starting material (33) (0.02 g, 6%), and dicyclopentadienyldi-

iron tetracarbonyl (4) (0.06 g) 27%), m. p. 188-190°C (lit.,5

192), V max (KBr) 1980, 1962, 1940, and 1911 (bridge C=O), and

1772 and 1762 cm-1 (terminal C=O) were eluted successively by

benzene. Tetraphenylcyclopentadienone-iron tricarbonyl (60)

(0.05 g, 12%), m.p. 178-180°C (lit., 33 180°C),V max (KBr) 2064,

2015, and 1996 cm-1 (terminal C=0) was eluted by pure acetone.

46 1, 2, 3, 4-Tetrachloro-5, 5, -dimethoxycyclopentadieiie

A solution of hexachlorocyclopentadiene (254g, 0.93 mol) in methanol (800 ml) was placed in a 3-1 two-necked round- bottomed flask equipped with a dropping funnel and reflux condenser. A solution of potassium hydroxide (120 g, 2 .14mol) in methanol (600 ml) was added dropwise from the dropping

funnel over a period of 2 h. The reaction mixture was stirred

for a further.couple of hours, then poured into chopped ice

(3 kg), and extracted with methylene chloride (3x250 ml).

The combined extract was washed with water, dried over anhydrous

magnesium sulfate, and evaporated in vacuo. The liquid residue

was distilled to-give 1, 2, 3, 4--tetrachloro-5, 5-dimethoxycyclo--

pentadiene (180 g, 73%), bop. 60-65°C at 0.2. mmHg (lit., 34 79-

84°C at 0.6 mmHg),

Octachloro-3a. 4.7.7a-tetrahydro-Lr. 7-riiethanoindene-l. 8-dione (39)

1, 2, 3, k-Tetrachloro-5, 5-dirr ethoxycyclopentadiene (2.2 g,

0.0083 mol) was added dropwise to concentrated sulfuric acid

(9 g) at 0-5°C. The mixture' was then poured onto crushed ice

(50 g), and the white solid was filtered with suction. The residue

was washed with water and dried in air to give a dihydrate of

octachloro-3a, 4, 7, 7a-tetrahydro-Li-, 7-methanoindene-1, 8-dione

(39) (197 g,94%), m. p. 155-160°C dec (1it,,35 157163°C dec).

The hydrate was recrystallized from petroleum ether

(90-110°C) to afford anhydrous octachloro-3a,4,7,7a-tetrahydro-

L, 7-methanoindene-1, 8-dione (39) (1.2 g, 67%), m. p. 164-166°C de c

(lit., 36 165-166°C) , V max (KBr) 1850 (bridge C=O), 1750 (=O))

and 1595 cm-1 (C=C).

47 Octachloro-3a,7a-dihydroindenone (40)

A solution of octachloro-3a,4,7,7a-tetrahydro-4,7-methane-

1,8-dione (39) (10.0g, 0.023 mol) in xylene (150 ml) was

allowed to reflux under nitrogen atmosphere for ca.5 h.

The mixture was cooled and the solvent was removed in vacuo.

The residue was then recrystallized from benzene to give

octachloro-3a, 7a-dihydroindenone (40) (8.0 g, 86%), m. p. 120-

121°C (lit.,37 123-124°C) (Found: C, 26.76 Cl, 69.80. Calc.

for C 9 0C1 8 C,, 26.51 Cl, 69.56%), V max (KBr) 1762. (C=0) and

1592 cm-1 (C=C). m/e 404 (M+), 406 (11++2) 5 408 (11++4), 410 (M++6),

412 (11+ 8), and 414 (M++10)

Hexachloroindenone (61)

A mixture of octachloro-3a,4,7,7a-tetrahydro-4,7-methano-

indene-1, 8-dione (39) (5.5 g, 0.013 mol) and water (100 ml)

was heated at 100°C for ca. 5 h. The mixture was cooled and

filtered with suction. The residue, was dried in air and recrystallized

from acetone to afford hexachloroindenone (61) (3-5 g, 82%).,

m. p. 149°C (lit., 35 149°C), V max (KBr) 1730 cm-1 (C=O) m/e

334 (M+) 336 (M++2), 338 (M++4), 3.40 (M++6), 342 (M++8), and

344 (M++10).

Attempted Diels-Alder Heactlon of uctacIIIoro-3a,7a-dihydroindenone

(40) with Maleic Anhydride

In an attempt to prepare the adduct (63), portions of

compound (1+0) were heated with maleic anhydride in refluxing benzene, dioxane and xylene.48 It was found that only starting materials were recovered in these cases. Furthermore, the mixture was allowed to react in tetralin in a seal tube.

However, it was found to recover a small amount of starting

materials and a black tar.

Reaction of Octachloro-3a,4,7,7a-tetra hydro-k, 7-methanoindene-

1,8-dione (39) with Iron Pentacarbonyl

A mixture of compound (39) (1.8 g, 0.-004 mol) and iron

pentacarbonyl (1.6 g, 0.008 mot) in xylene (50 ml) was refluxed under nitrogen atmosphere for ca, 12 h. The reaction mixture

was cooled, filtered and the residue was'washed with acetone.

The combined filtrate was evaporated in vacuo. The residue was

then recrystallized from acetone to give hexachloroindenone

(61) (0.8 g) 60%), which was identical in all respects (mixed

M.P., j.r. and mass spectra) with an authentic sample.

Reaction of Octachloro-3as 7a-dihydroindenone (40) with Iron

Pentacarbonyl

A mixture of compound (40) (0.5 g,-0.0012 mol) and iron

pentacarbonyl (0.5 g, 0.0025 mol) in xylene (50 ml) was refluxed

under nitrogen atmosphere for ca.12 h. The reaction mixture

was cooled, filtered and the residue was washed with acetone.

The combined filtrate was evaporated in vacuo. The residue was

then recrystallized from acetone to afford hexachloroindenone

(61) (0.25, 62%)2 which-was identical in all respects (mixed

m. p., i.r. and mass spectra) with an authentic samole. 49 Cyclopentanone--2, 2, 5, 5-d4, (20)

Cyclopentanone (33.6 g, 0.4 mol) was mixed with deuterium oxide (2:2,0 g,0.6 mol) and anhydrous potassium carbonate (0.1 g) and the mixture was refluxed for ca. 24 h. The aquoous layer was removed, fresh deuterium oxide and anhydrous potassium carbonate were added, and the refluxing repeated. Six exchanges

followed by drying over anhydrous magnesium sulfate and distillation

to afford cyctopentanone-2, 2, 5, 5-d4. (20) (8 g, 24%)

Deuter. iated 3a, 4, 7, 7a--Tetrahydro--4, 7-tnethanoindene-1, 8-dione (21)

Compound (21) was prepared according to the procedures

described for compound (6) using cyclopentanone-2, 2, 5, 5-d4 (20)

as starting material. From the N.M.R. spectrum (see NM'5) of

(21), it was calculated that ca. 70% deuterium was incorporated.

Reaction of Deuteriated 3a, 4, 7, 7a-Tetrahydro, 7-methanol ndene_

1,8-dione (21) with Iron Pentacarbonyl

Compound (21) was treated with iron pentacarbonyl in a

similar manner as that described for compound (6). The N.M.R.

spectrum (see NMP--6) taken for the isolated product was

consistent with the compound having the structure (24),.

50 LIST OF SPECTRA

A. NMR SPECTRJ

1. 3a,4,7,7a-Tetrahydro-4,7-methanoindene 1,8-dione (6) 53

2. 3a,7a-Dihydroindenone(8) 54

3. l Indanone 55

56 4. Maleic Anhydride Adduct (43)

5. Deuteriated 3a,4,7,7a-Tetrahydro-4,7-methanoindene-1,8-

dione (21) 57

6. Deuteriated 1-Indanone (24) 58

7. 3a, 4, 7,7a-Tetrahydro-4, 7-methanoindene-1, 8-dione

Bisethylene Ketal (5) 59

8. 3a,4,7,7a-Tetrahydro-4,7-methanoindene-1,8-dione

8-Ethylene Ketal (30) 60

9. 2,4-Dibromo-3a,4,7,7a-tetrahydro-4,7-methanoindene-l,8-

dione (32) 61

10. 2, 4-Dibromo-3a,,7a-dihydroindenone (54) 62

11. 4-Bromo-l-indanone (55) 63

12. 2,4-Dibromo-l-indanone (57) 64

13. Maleic Anhydride Adduct (58) 65

14. 4., 5, 6, 7-Tetraphenyl-3a, 4, 7, 7a-tetrahydro-4, 7-methano-

indene-8-one (33) 66

15. Tetraphenylcyclopentadienone (59) 67

B. IR SPECTRA.

la. 3a,4,7', 7a-T etrahydro-•4-, 7-methanoindene-1, 8-dione (6) 68

b. Deuteriated 3a, 4, 7, 7a-Tetrahydro-4, 7-methanoindene-

1,8-dione (21) 68 51 2a. 3a,7a-Dihydroindenorse (8) 69

b. l- Indanone 69

3a. Maleic Anhydride Adduct (43) 70

b. Maleic Anhydride Adduct (58) 70

4a. 2,4-Dibromo-3a,7a-dihydroindenone (5) 71

b. 2,,4-Dibromo-l-indanone (57) 71

C, 4-Bromo-l-indanone (55) 71

5. Tetraphenylcyclopentadienone-iron Tricar.bonyl (60) 72

6. Dicyclopentadienyldi-iron Tetracarbonyl(4) 73

7a. Octachloro-3a,4,7,7a-tetrahydro-4,7-methanoindene-

1,8-dion.e (39) 74

b. Octacnloro-3a,7a-dihy.droindenone (40) . 7.4

C, Hexachloroindenone (61) 74

C. MASS SPECTRA:

1. 2, 4-Dibromo-3a,7a-dihydroindenone (54) 75

2. Maleic Anhydride Adduct( 43) 76

3.. Maleic Anhydride Adduct (58) 77

4.. Octachloro-3a,7a-dihydroindenone (40) 78

5. Hexachloroindenone (61) 79

52 55

Solvent: CDCL3

9 8 7 6 5 4 3 2 1 NMR--1. The NMR spectrum of 3a,4,7,7a-Tetrahydro-4,7-methanoindene-1,8-drone (6). 54

solvent: ccl

9 8 7 6 5 4 3 2 1 NMR-2. The NMR Spectrum of 3a,7a-Dihydroindenone (8). Solvent: CC1

7 6 5 4 3 2 NMR-3. The NMR Spectrum of 1-Indanone. 56

Solvent: CD3COCD3

9 8 7 6 5 4 3 2 1 NMR-4. The NMR Spectrum of Maleic Anhydride Adduct (43), 57

Solvent: CDC13

9 8 7 6 5 4 3 2 1

NMR-5. The NMR Spectrum of Deuteriated 3a,,4.,7,7a-Tetrahydro-4,7-methanoindene-1,8-dione (21). 58

Solvent: CC14

9 8 7 6 4 3 2 1 ppm

NMR-6. The NMR Spectrum of Deuteriated 1-Indanone (24). 59

Solvent: CDC1

9 8 7 6 5 4 3 2 1 NMR-7. The NMR Spectrum of 3a,4, 7, 7a-Tetrahydro-4, 7-me'thanolnden.e-1, 8-dione Bisethylen Ketal (5}, 60

Solvent: CDC13

9 8 7 6 5 4 3 2 1

NMR-8. The NMR Spectrum of 3a,4,7,7a-Tetrahydro-4,7-methanoindene-1,8-dione 8-Ethylene Ketal (30), 61

Solvent: CDC13

9 8 7 6 5 4 3 2 1

NMR-9. The NMR Spectrum of 2, 4-Dibromo-3a, 4,7, 7a-tetrahydro-4, 7-methanoindene-1, 8-dione (32), 62

Solvent: CCl4

9 8 7 6 5 4 3 2 1 NMR--10. The NMR Spectrum of 2,4-Dibromo-3a,7a-dirydroindenone (54). Br

solvent:ccl4

9 8 7 6 5 4 3 2 1 ppm

NMR-II. The NMR spectrum of 4-Bromo-l-indanone (55), Br

Solvent: CCI4

9 8 7 6 5 4 3 2 1 ppm NMR-12. The NMR Spectrum of 2,4-Dibromo-l-indanone (57). 65

Solvent:CD3COCD3

9 8 7 6 5 4 3 2 1 ppm NMR-13. The NMR Spectrum of Maleic Anhydride Adduct (58). 66

Solvent: CDCI3

9 8 7 6 5 4 3 2 1 ppm

NMR-14. The NMR Spectrum of 4,5,6,7-tetraphenyl-3a,4,7,7a-tetrahydro-4,7-methanoindene-8-one (33). 67

Solvent: CDCI3

NMR-15. The NMR Spectrum of Tetraphenylcyclopentadienone (59). WAVELENGIHINMICRONS

WAVENUMDERCM

IRla. The Infrared Spectrum of 3a,4,7,7a-Tetrahydro-4,7-

methanoindene-l,8-dione (6).

WAVELENGIHINMICRONS

WAVENUMDERCM

Irlb. The Infrared Spectrum of Deuteriated 3a,4,7,7a-Tetrahydro-

4,7-methanoindene-l,8-dione (21). 68 WAVFLENGTHINMICRONSWAVFLENGTHINMICRONS 3.5 4 4.5 5 5 5.5 6 6.5 7 7.5 8 9 10 11 12 14 16 16 18 70 75 80

3000 2500 2000 2000 1800 1600 1200 1200 1000 900 500 600 500 400 WAVENUMBERCM

IR-2a. The Infrared Spectrum of 3a,7a-Dihydroindenone (8).

WAVELENGTHINMICRONS 4 4.5 5 5 5.5 6 6.5 7 7.5 8 9 10 11 12 14 16 161820

3000 2500 2000 2000 1800 1600 1400 1200 7000 800 500 400 500

IR--2b. The Infrared spectrum. of 1-Indanone.

69 WAVELENGIHINMICRONS

WAVENUMBERCM

IR-3a. The Infrared Spectrum of Maleic Anhydride Adduct (43).

WAVELENGIHINMICRONS

WAVENUMBERCM

IR-3b. The Infrared Spectrum of Maleic Anhydride Adduct (58).

70 IR-4a.The Infrared Spectrum of 2,4-Dibromo-3a,7a-dihydroindenone (54).

IR-4b. The Infrared Spectrum of 2,4-Dibromo-l-indanone (57)

IR-4c. The Infrared Spectrum71 of 4-Bromo-l-indanone (55). 72

IR-5. The Infrared Spectrum of Tetraphenylcyclopentadienone-iron Tricarbonyl (60). 73

IR-6. The Infrared Spectrum of Dicyclopentadienyldi-iron Tetracarbonyl (4). IR-7a. The Infrared Spectrum of Octachaloro-3a,4,7,7a-tetrahydro-

4,7-methanoindene-l,8-dione (39).

IR-7b. The Infrared Spectrum of Octachloro-3a,7a-dihydroindenone (40).

IR-7c. The Infrared Spectrum of Hexachloroindenone (61). 74 M+2 Br 290

100 Br M*-Br79/[M+2]-Br81

[M+4]-Br81/[M+2]-Br79

209 211

1O2

60 M+ M+4 75 288 292

40 RelativeIntensity,% 149

101 152

20 77 90 181183 . 293 91

260

80 100 120 140 160 180 220 240 200 260 280 300 m/e

MS-- 1. The Mass Spectrum of 2,4-Dibromo-3a, 7a-dihydroindenone(54). C6H6+

100

[M-CO-CO2]+ 80 158

M+ 60

230

129

RelativeIntensity,% 40

184 76

20 105 115 51 [M-CO]+ 64 39 150 202

174

20 40 60 80 100 120 140 160 180 200 220 240

m/e

MS-2. The Mass Spectrum of Maleic Anhydride Adduct (43). 158 100

Br C5HOBr79+ 156 Br

128 RelativeIntensity,%

C6H5+ M+2 40 77 77 388 [m+2]-CO 160 360 102 183185 51 79 228230 M M+4 386390 20 M-CO [M+4]-CO 63 358362 127 391

40 60 120 160 200 240 280 320 360 400

m/e

MS-3. The Mass Spectrum of Maleic Anhydride Adduct (58). C1 C1 C1 377

100 C1 C1

C1 C1 C1 373

375

369

308 40

310 RclativoIntensity,78% 336 301 345 20 238 M+4 377 M+2 273 312 236 408 M+6 299 406 M+ 201 410 M+8 415 412 M+10 414

200 220 240 260 300 340 360 380 400 420 280 320

MS-4. The Mass Spectrum of Octachl.oro-3a, 7a-dihydroindenone (40 ). 301

100

336 M+2

333 M+4

303

299 60

RelativeIntensity,% M+ 334

79 340 M+6

273

305 20 238 271 275 166 236 M+8 149 201 342 M+10

344

140 160 180 200 220 240 260 280 300 320 340 360 m/e

Ms-5. The Mass Spectrum of Hexachloroindenone (61) REFERENCES

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