N-quaternary compounds. Part XL. Syntheses of 1a,6a-dihydroindeno[1,2-b]azirin-6(1H)-ones and isomerisation to isoquinolinium derivatives

Abstract

Isoquinolinium-4-olates (5) have been synthesised from the valence isomeric 1a,6a-dihydroindeno[1,2-b]azirin-6(1H)-ones (4) by photochemical ring-opening. The thermally disallowed conrotatory ring-opening proceeded less readily. The N-arylaziridines (4; R = Ar) were prepared by photolysis of 3-aryl-3a,8a-dihydroindeno-[1,2-d]triazol-8(3H)-one derivatives (3); 3-alkyl derivatives did not react. Thermolysis was less successful and may yield the isomeric indan-1,3-dione monoimine. The triazolones (3) were formed by addition of azide to inden-1-one.