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Synthetic Studies in the Preparation of Various I II I.II l‘I‘ III IIII ‘II‘III I 01—: 00—8 I '4 .mmm SYNTHETIC STUDIES IN THE PREPARATION OF VARIOUS PYRAZOPYRROMETHANES, PYRAZOPYRROMETHENES AND PYRAZOPYRROKETONES AS POSSIBLE ROUTES TO A 4,7:13,16 - DIIMINO - 2,26:18,20 - DIETHYLENE-O, 11 - N,N’ - HYDRAZINE - 22,24 - N,N'OIIMINE- 1,19 - DIAZA(26)ANNULENE Thesis for the Degree of M. S. MICHIGAN STATE UNIVERSITY JAMES EDWIN MACDONALD 1976 “L ' - ._"‘. m- . n‘ . u . .- . - _ _ ,_-__ _"__ -_--_- - -qH—O_ ‘5‘- —--»—-” MICHIGAN IIIIIIIIIIIII MIIIIII STATE UNIVERSITYIIIIIIIIIIII B IIIIIIII 01591 3852 V ABSTRACT SYNTHETIC STUDIES IN THE PREPARATION OF VARIOUS PYRAZOPYRROMETHANES. PYRAZOPYRROMETHENES AND PYRAZOPYRROKETONES AS POSSIBLE ROUTES TO A 4,7:13,16-DIIMINO-Z,26:18,20-DIETHYLENE-9,TT-N,N'-HYDRAZINE-22,24- N,N'DIIMINE-T,T9-DIAZA[26]ANNULENE By James Edwin Macdonald The 4,7:l3,16-diimino-2,26:l8,20-diethylene-9,ll-N,N'-hydrazine- 22,24-N,N'diimine-l,l9-diaza[26]annulene is proposed as the object of a synthetic scheme, as it should have interesting physical and chemi- cal properties. The mode of approach is based on the precedence of known pyrrole chemistry. The methods employed involve the reaction of pyrroles that have free a positions with 3,5—disubstituted pyrazoleacid- chlorides, pyrazoleketones and pyrazolealdehydes or hydroxymethyl- pyrazoles under a variety of conditions. In no case investigated could the desired model condensations be achieved, and these methods do not appear to be a viable route to the proposed system. SYNTHETIC STUDIES IN THE PREPARATION OF VARIOUS PYRAZOPYRROMETHANES, PYRAZOPYRROMETHENES AND PYRAZOPYRROKETONES AS POSSIBLE ROUTES TO A 4,7:l3,T6-DIIMINO-2,26:lBJK¥DIETHYLENE-9,ll-N,N'-HYDRAZINE-22,24- N,N'DIIMINE-T,TQ-DIAZA[26]ANNULENE By James Edwin Macdonald A THESIS Submitted to Michigan State University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE 1976 ACKNOWLEDGEMENTS The author wishes to express his sincere gratitude to Dr. Eugene LeGoff for his guidance and aid during the course of this research. Thanks are also due to my fellow graduate students, especially to Houston Brown, who contributed to making this degree possible and the last two years agreeable. ii TABLE OF CONTENTS LIST OF FIGURES ......................... INTRODUCTION .......................... DISCUSSION OF RESULTS ...................... EXPERIMENTAL SECTION ...................... 3-Diazo-2,4-pentanedione(ll) ............... 4-Methyl-3,5-diacetylpyrazole(l2) ............. Pyrromethenes(l3) from 4—methyT-3,5-diacetylpyrazole(l2) . 3,5-Dimethyl~4-carboethoxypyrromethene(l3a) of (12) . 3,5-Dimethyl-2-pyrromethene(l3b) of (12) ......... 3,5-Dimethyl—4-ethyl-2-pyrromethene(l3c) of (l2) ..... 4-Methyl-3,5-dithioacetylpyrazole(l4) ........... Pyrrolidine fluoroborate(l5) ............... 3,5-Bis(acetylpyrrolidiniminium fluoroborate)-4- methylpyrazole(l6) .................. 3,5-Dicarboxaldehydepyrazole(l7) ............. 3,5-Bis(glyoxate)-4-methylpyrazole(l8) .......... 3,5-Bis(diacetatemethyl)pyrrole(l9) ............ 3,5—Pyrazoledicarboxaldehyde(l7) by an adaption of the method of McFadens and Stevens ............ Pyrazole,3,5—dicarboxaldehyde by the Sonn-Muller Method N-phenylamides from esters .............. B-Anilinoacrolein(22) ................... Diazoacetaldehyde(23) ................... 3-Carboxaldehyde-S-carbethoxyp razole(24)' ......... 2-Pyrro-3-(5-carboethoxypyrazoImethene(25) ........ Reduction of pyrazopyrromethene(25) with zinc ....... Reduction of pyrazopyrromethene(25) with SnCl ...... Reduction of the pyrazopyrromethene with NaBH4 ...... Oxidation of the pyrazopyrromethene(25) with ceric amonium nitrate .................... Pyrazole-3,5-diacid chloride ............... 3,5-Bis(2-pyrrocarbonyl)pyrazole(28) ........... l-Benzylpyrazole—3,5-dicarboxylate(29) .......... Benzylpyrazole-3,5-diacidchloride(30) ........... l-Benzyl-3,5-bis(2-pyrrocarbonyl)pyrazole(3l) ....... Bromination of 3,5-dimethylpyrazole(32) .......... 3,5-Dimethyl-4-carbethoxy-l-pyrazoleamide(33) ....... Bromination of 3,5-dimethyl~4-carbethoxy-l- pyrazoleamide(34) ................... 3,5-Bis(hydroxymethyl)pyrazole(35) ............ 3,5-Bis(methyleneacetate)pyrazole ............. 30 3-Hydroxymethyl-5-carbeth oxypyrazole(37) ......... 30 Pyrazopyrromethanes from pyrazole(37) ........... 30 3-Carbet hyoxy-Z,4-pentanedione(37) ............ 3l l ,5-Dibromo-3-carb etho xy-2 ,4-pentanedione(38) ...... 3l Nucliophilic displacement on (38) with pyrrole ...... 31 Nucleophilic displacement on (38) with hydrazine ..... 32 Nucliophilic displacements on (38) with acetate ...... 32 Nucleophilic displacement on (38) with methanol ...... 32 Tris(3-phenyl-2,4-pentanedionato)chromium III (39) . 33 Tris(l,5-dibromo-3—phenyl-2,4-pentanedionato)- chromiumIII(40) .................... 33 BIBLIOGRAPHY .......................... 34 iv LIST OF FIGURES Figure Page 1 The proposed diaza[26]annulene ................ l 2 Pyrrole and pyrazole ..................... 2 3 Dipyrroleketone, dipyrromethene, and dipyrromethene ..... 2 4 Pyrazopyrroketone, pyrazopyrromethane, and pyrazopyrromethene ...................... 2 5 The synthetic scheme ..................... 3 6 The methene condensation ................... 5 7 Thioketones from ketones ................... S 8 Aldehydes from acetyl groups ................. 6 9 Thiele's method ....................... 7 l0 An acid chloride dimer .................... 9 ll The preparation of l-benzylpyrazole-3,5-diacid ........ l0 l2 Methane formation ...................... ll 13 Possible reaction of l,5-dibromo-2,4-pentane diones ..... l4 l4 A possible route to substituted pyrazoles .......... l5 15 A possible route to the macrocyclic ring ........... l5 16 A possible multistep route to the desired diaza[26]annulene . l5 INTRODUCTION Porphyrins are important hetrocyclic aromatic systems that have been intensively studied. An interesting and perhaps useful idea is to expand the porphyrin moiety into an extended ring structure like the diaza[26]annulene in Figure l. \\ '\\ ‘\\ ‘\\ \\ NH MEN HN \ H H \ N N—N N.» \ I / / / / Figure l. The proposed diaza[26]annulene This expanded [26]annulene would be novel in that it may form bimetallic compTexes. In that case mixed metal and mixed metal oxidation states with unusual physicaI properties could be observed. This might lead to the development of novel catalyst systems or to organic conductors. Annulenes of this size are unusual in that calculations show that they should show little if any aromatic charactor.2 Tests of this prediction could be interesting. The purpose of this work is to apply the methods developed in porphyrin chemistry to the formation of the proposed diaza- [26]-annulene. This was undertaken using pyrroles and pyrazoles as building blocks (Figure 2). The models for the reactions were [a 4/”) D11 N H H pyrrole pyrazole Figure 2 derived from the well studied coupling of pyrroles to form a,a' dipyrromethanes, methenes and ketones (Figure 3). \ \N NJ \ N~ H H H H dipyrroleketone dipyrromethene dipyrromethene Figure 3 Following these models the unknown pyrazopyrromethane, pyrazopyrro- methene and pyrazopyrroketone classes of compounds in Figure 4 might be synthesized by the condensation of pyrazoleacidchlorides, pyrazole ketones and aldehydes or hydroxymethylpyrazoles with ant: unsubstituted pyrrole. /\ // /I / /n \ \ N/N N N,N N/ N/N N\ H H H H H pyrazopyrroketone pyrazopyrromethane pyrazopyrromethene Figure 4 3 If any of the model systems tested work then the condensation in Figure 5 would be a reasonable approach to the diaza[26]annulene, (x is any group that is found to react well with pyrrole). Figure 5. The synthetic sceme The difficulties found in this approach will be discussed and other potential routes to this system will be considered as future possibilities. DISCUSSION OF RESULTS One approach to this proposed diaza[26]annulene system would be to condense two pyrromethanes with two properly functionalized pyrazoles as seen in Figure 5. The pyrromethanes are not difficult to form and are well known intermediates in porphyrin chemistry.5 The objective of this research then is to investegate the unknown con- densations of pyrroles with pyrazoles to give methene, methane or ketone linkages as this is the crucial step in the synthesis of the target macrocycle in Figure 5. This investigation can be approached with the least difficulty by first attempting the reactions with small model systems, and if their results are favorable then extend-- ing the reaction to the larger system as in Figure 5. One approach to the proposed macrocycle is exemplified by the model reaction between 4-methyl-3,5-bis(acetyl)pyrazole(12) and pyrrole which should lead to a 4-methyl-3,5-bis(a-pyrromethene) pyrazole(l3). C? ./ // / +_22 [Z713> ___;> ’/ ‘/’ ,/’ / ‘\‘ \\ HN"N N 6N, HN—N \ (12) (13) This reaction has many precedents in the reactions of pyrroles with other aIdehydes and ketones, for example, the formation of a pyrromethene salt by the acid catalyzed reaction of pyrrole and 6 3,4,5-trimethylpyrrole carboxaldehyde as in figure 6. HB H H Figure 6. The methene condensation The reaction of the pyrazole was carried out in hot ethanol, methanol or hot acetic acid. In all cases the mixture exhibited two peaks in the visible spectra, one at 485nm and one at 605nm. They arose from two different chromophores since the absorption ratio between the two peaks varied over a wide range as the reaction progressed. It was clear from this that the reaction gave a mixture of products. Attempts to separate the two products by crystalization did
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