Adição de IN3 a derivados de acidos -alquil cinamicos : obtenç2o de 2-alquil-3-fenil-1-azirinas e 3-azido-2-azetidinonas

AUTOR(ES)
DATA DE PUBLICAÇÃO

1987

RESUMO

The present study began with the preparation of 2- phenyl-3-carbomethoxy-1-azirine (16) with the intention of examining the reactivites of the two electrophilic centers of the molecule, that is, the carbon of the imine group and the carbonil of the ester. Reaction of system 16 with hidrazine in benzene produces the 4-aminopyrazol-3-one 26, intercepted in the form of the Schiff base 37 upon reaction with benzaldehyde and as the enaminone 38 upon reaction with acetyl acetone. 2-Phenyl-3-carbomethoxy-3-methyl-1-azirine (50) which contains an additional substituent on C3, when submitted to the same reaction conditions, forms the heterocycle 3-phenyl -5-methyl-1,2,4-triazin-6-one (56). During the preparation of azirine 50, for which the yield was never superior to 21%, it was observed that iodo azide adducts 57 and 58 which presente inverted regiochemistry when compared to the analogous adduct precursors of 16 survived the dehydrohalogenation slep, and that these systems, when exposed to treatment with KOH in methanol produce the vinyl azides 77 (E) and 78 (Z) which, upon heating, permit the isolation of 2-methyl-3-phenyl-1-azirlne (79). With the intention of studying the generality of the method with respect not only to the obtention of isomeric 1-azirines of type 79 but aIso with respect to electronic and spacial effects in lhe formation of iodo azide adducts, the previously unknown 2-phenyl-3-carbomethoxy-3-ethyl-1-azirine (122) was prepared, which required the previus synthesis of the a -ethylcinnamic acid. For this last azirine, obtention or the unexpected adducts 123 (Z) and 124 (E) was again observed this time in greater quantity than in the case of adducts 120 which led to azirine 122. The iodo azides 123 and 124 were obtained with loss of the regio- and stereospecificity previously cited for addition reactions of IN to olefins. Finally, utilizing this observation with view towards the preparation of 2-azetidinones (b-lactams) through intramolecular substitution, whose synthetic interest lies in the possibillity of these systems being used as intermediates in the obtention of biologially active compounds, N-benzyl-a -methyl cinnamamide (128) and N-t-Bu-a-methyl cinnamamide (141) were prepared which, in analogous fashion, furnished iodo azide which under basic conditions of Phase Transfer Catalysts, afforded the diastereomertc 3-azido-2-azetidinones 134, 135, and 146.

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