The reaction of benzenesulfonyl azide with cis-endo and cis-exo norbornene-5,6-dicarboxylic acid anhydrides and methyl esters. The formation of endo aziridines from exo triazolines

Abstract

Benzenesulfonyl azide reacts with cis-endo (Ia) and cis-exo-norbornene-5,6-dicarboxylic anhydrides (IIa) and with the corresponding cis-exo-dimethyl ester (IIb) in refluxing carbon tetrachloride to give predominantly endo aziridines. Under identical conditions the cis-endo dimethyl ester (Ib) gives exclusively the exo aziridine and under photolytic conditions the cis-exo and cis-endo anhydrides and dimethyl esters give almost exclusively exo aziridines. At room temperature, the cis-exo dimethyl ester IIb gives predominantly the exo aziridine, and p-methoxybenzenesulfonyl azide reacts with the endo-anhydride Ia in refluxing carbon tetrachloride to give an even greater ratio of the endo aziridine. The exo-1,2,3-Δ 2-triazoline XIIIa prepared from the exo anhydride and phenyl azide, on pyrolysis in decalin, gives an almost 1:1 ratio of the exo and endo aziridine. A mechanism is proposed to account for the above observations which involves the conversion of exo-1,2,3-Δ 2-triazolines to endo aziridines via a 3-diazomethylcyclopentane-2-carboxaldehydeimine intermediate (XI).