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Organic Seminar Abstracts ; . ' ' :»: ?•:?•*;. nhh.::-;ftw $fc JKfiHSBl ' '>:!:ii')jii";V ;' ; URHBhhSI • : ' . ' : ' 1 : ' . i h ffi , IHHi" ' v y9 H h v • : iilSlilifllil IB1L i :,r HHHBfflH 1%•'<.!':'. HI "•:'. ;''• „/: •.'''.. ion I', aWgw RMwjxn L I E> RAHY OF THE U N IVERSITY Of ILLINOIS G. 54-7 lJ>6s ,t.-2 P Return this book on or before the Latest Date stamped below. Theft, mutilation, and underlining of books are reasons for disciplinary action and may result in dismissal from the University. University of Illinois Library 004-2 W66 L161— O-1096 V) 1 ORGANIC SEMINAR ABSTRACTS 1963-1964 SEMESTER II Department of Chemistry and Chemical Engineering University of Illinois Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/organicsemi1963642univ : n SEMINAR TOPICS II Semester I963-I964 Recent Progress in the Deamination of Aliphatic Amines R. Feiertag 1 The Origin of Potential Barriers to Internal Rotation W. A. Bernett 10 The Effect of High Pressure on Reaction Rates Linda R. Brammer 19 Mechanism of Heterogeneous Catalytic Hydrogenation L. Walker . 28 The Structure and Synthesis of the Onocerins Kermit Carraway ....... 37 Recent Mechanistic Studies of Base-Catalyzed Olefin .Migration Reactions D. Druliner h6 The Question of the Carbonium Ion From Solvolyses of 2-Norbornyl Derivatives Thomas P. Doherty 55 Displacement Reactions on Silicon. Recent Developments F. Mo Vigo ......... 63 Intramolecular Attack at C-19 of Steroids by a Neighboring Oxygen Function Elizabeth McLeister ..... 71 The Karplus Rules and Conformational Analysis J. Miesel .......... 80 The Pummerer Reaction- Bruce M. Monroe ....... 89 Recent Chemistry of Unsaturated Azlactones Allan C. Buchholz ...... 97 Solvent Isotope Effects on Acid Dissociation Constants and Acid Catalyzed Reactions Raymond Feldt ........ 106 Cyclizations of Propynyl Carbamates and Propynylureas Barry E. Galbraith ..... 115 Chemistry of Sulfenes Robert Y. Ning ....... 124 Replacement of Oxygen with Sulfur Using Fnosphorus Pentasulfide Ronald Hackler 130 Carbonyl-Containing Three -Membered Rings as Reaction Intermediates D. W. Lamson 139 . o^ -1- RECENT PROGRESS IN THE DEAMINATION OF ALIPHATIC AMINES Reported by R. Feiertag February 10, 1964 Introduction , --The deamination of aliphatic amines has been an area of, intense chemical interest for some time- In recent years more information about the reaction has been obtained from a number of aliphatic systems „ It is the purpose of this ab- stract to report the results of several investigations into the nature of the inter- mediates involved in deamination. A general review of deamination has appeared (i), as well as more specific re- views on deaminations involving ring expansion (Demjanov reaction) (2) , bicyclic sys- an<i tems (3) ? the cyclopropylcarbinyl system (4,5.96,7), substituted ethylamines (8). Deamination of Sub s tituted Ethyl and Propyl Amines . --Collins and coworkers have studied the deaminations of a number of substituted ethyl and propyl amines and amino alcohols o These studies have been carried out using amines labeled with carbon-l4, optically active amines, and optically active carbon-Ik labeled amines. In every case extensive rearrangement took place,. Collins* earlier work, which has been re- viewed (8), indicated that these rearrangements did not take place through bridged phenonium ionsc Instead, a mechanism in which open carbonium ions whose formation was controlled by the ground state conformations of the molecules was used to explain the observed results . A kinetic treatment of the data gave support to this mechanism (9). A number of additional experiments were designed to test the hypothesis that only open carbonium ions are involved in these deaminations „ The results support the 14 earlier conclusions. Deaminations of (+) and (-) -1,2,2 ~triphenylethyl-l-C -amine (i) were carried out in water to which a small amount of acetic acid had been added at temperatures ranging from -2° to 3606 (10). The major product was 1,2,2-tri- phenylethanol (II); the remainder (about 10$) was composed of 1,2,2-triphenylethyl acetate and 1,1,2-triphenylethylene. In every case there was net retention of eon- Ph2CHCHPh •» Ph2CHCHPh + Ph2CHCHPh + Ph2(>CHPh I I I NH2 OH OAc I II figuration with some racemization, and rearrangement of the C14 label. The carbinols were resolved into samples of completely retained configuration and into racemic mix- tures o Each sample was then oxidized to benzophenone which was assayed, for radio- activityo This gave the activity at C.2 and therefore the percent rearrangement of 14 14 C . From the percent C rearrangement in the optically active carbinol of retained 14 configuration and that i.n the racemic mixture, the percent C rearrangement in the carbinol of inverted configuration may be calculated. The results are given in Table 1. Table 1 Starting $ Overall 4 Material Retention J_C^ —Rearrangement in Product Carbinol II Retained Inverted Configuration Racemic Configuration (+)-I 6k 26.5 28.1 29<7 (-)-I 70 20.6 2k. 5 28.4 Reaction exclusively through bridged phenonium ions (Figure l) should lead to product with retained configuration in which 33$ of the label is found at C.2, and product with inverted configuration in which all the label is found at C.2. But in both cases more rearrangement of the label, took place in the product with inverted c r -2- H H OH H OH Hi I "c — C: + -c- 'H Hi r H Hi Hi V H Hi Hi Hi Retained config- Retained config- uration. Label uration. Label at C.I at C.2 Hi OH Hi OH Hi Hi v ^v * .-Hi H^ c — v ^C— Cr "• — H^1 \> S l>H Hi v*H Hi H H Hi Retained config- Inverted config- uration. Label, uration. Label at C.l at C.2 Figure 1 configuration than in that with retained configuration, On this basis bridged ions were ruled out. If It is assumed that the amine exists primarily in its most- stable conformation ( III) , the above results may be explained on the basis of classical open carbonium ions. The reaction mechanism shown in Figure 2 was proposed. In this mechanism, none of the intermediate H^S-^Th ions are subject to rearward attack, the ionic site being protected Fh by the phenyl group on the adjacent carbon atom. A kinetic treatment III of the above mechanism ( 11.) led to a series of equations which were solved for the mole fractions of the products. The observed and calculated mole fractions were in good agreement, indicating the compatibility of this mechanism with the experimental results. -Rearranged (+) -Unrearranged Ph Carbinol Carbinol Ph H Hi H r H Hi 1* X® */ Vc c-pn £ C-—Hi l kph Hi H Ph ^* Fn .'""t^-^ -^kph k2 \ Hi H ( -) -Unrearranged ( -) -Unrearranged Carbinol Carbinol Figure 2 Additional experiments were carried out in order to further test the validity of the above conclusions. Optically active erythro-l-amino-l,2-diphenyl-2-propanol- 14 1-phenyl-C (IV)(12), erythro- and threo -l-amino-l~phenyl-2-p-tolyl-2-propanoI-2- C14 (V)(13); erythro - and threo -l-amino-l-phenyl-2-p-methoxyphenyl-2-propanol (VI), and erythro - and threo-l-amino-l-phenyl-2-o-tolylpropanol (VIl)(l4) were prepared p2 IV. R = Ph, R 1 = Hi* 1>R V. R a p-CH Ph, R' = Ph L-erythro L-threo 3 ^Xh VI. R = P-CH3OH1, R' = Ph CH 3 VII. R -- 0-CH3H1, R' = Ph ) and subjected to sem.ipinacolic deamlnation. The products were the corresponding ketones ( VTII) in yields of 7C-9£$° If bridged ions are important, it would be ex- pected that the electron donating ability of the p-methoxy and £-methyl groups would cause a larger amou iging for ions from V and VI Ar than for the corresponding ion from IV* This would cause Hi B a greater amount of inversion in the case of the er^rthro ttl isomerso If open classics ionium Ions arising from the most stable ground, state conformer are importer At VIII erythro-IV, -V and -VI should aU give the same amount of inversion, and threo- -7 and -VI should give a greater amount of retention than the corresponding erythro isomers (Figure 5) • Moreover., "' ^Z!*i£2- and- ^Eoo-VII , having different steric requirements, should give pro- ducts in ratios different from those of the other three. Ejcperimentally it was found that in the deaminations of erjrthrc-IV, -V, and -VI there was 73f> y fi&, and 77$ Inversion, respectively. Deamlnation of threo-V and -VI led to products with 57$ and ?9$ retention, respectively. In contrast, erythi ni gave 96$ inversion and threo -VTI, k^f> retention. These results were explained by the mechanisms shown in Figure 3 In which open carbonium ions arising from the most stable ground-state con- formers of the molecules are the intermediates. In the case of vl.< the bulky o-tolyj group makes rotation about the carbon -carbon bond difficult in the intermediate ions, leading to greater amounts of inversion in the erythro case. Deamlnation of threo VII leads to anomalous results when discussed in terms of this mechanism. NH2 CHs Fh H. OH HOyHK/jH3 J Fh<^>3 H Ar Ar L-(-)-ervthrp rersion Ar W-2 HOn^-CAt <e :?h^-^K CH Retention 3 L-( - -threo Of special interest was the deamlnation of IV (12) L-(+)-IV gave the ketone :IX (Figure 4) which was converted to its cxlme. This was reduced to give (+)-Xa end (-)-Xb, which are both optical isomers and isotope position isomers. The amine (+) Xa was then subjected to deamlnation^ yielding the alcohols erythro- and three -XI „ The products were degraded and counted to determine the position of the isotope la- beling. These transformations are shown in Figure 5. 73 >& W-2 HCVfvCHa ^H H JIJb**.* 0=fY)-CH3 > >vO + Fh Fh* 26„9# L-(+)~IV IX (+)-Xa Figure k The results of this double deamlnation were interpreted (in the case of (+)-Xa) as follows (Figure 6): It is assumed that the conformation shown for (+)-Xa in Fig- ure 5 is the only important ground state conformation.
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