Reactions of a New Family of Amide Derivatives of Phenanthridinium Azomethine Ylides with Dipolarophiles

Abstract

Reaction of a series of N-alkyl- and N,N-dialkylbromoacetamides 1a-1e with phenanthridine afforded quaternary phenanthridinium salts 2a-2e. These compounds treated with triethylamine form azomethine ylides which undergo a cycloaddition reaction with activated C=C bond, giving 3-(N-alkylcarbamoyl)-1,2,3,12b-tetrahydropyrrolo[1,2-f]phenanthridines 3a-3e, 4c, 5c, 6c or 3-(N-alkylcarbamoyl)-2,3-dihydropyrrolo[1,2-f]phenanthridine 7c. Their stereochemistry was studied by NMR spectroscopy. The best results were obtained with fumaronitrile as a dipolarophile. It has been found that the ylides react in syn conformations but if 1-adamantyl moiety is bound to the ylide, it reacts in anti conformation, too. The azomethine ylides show a very poor reactivity towards dimethyl fumarate or dimethyl maleate. Yet we could prepare products for ylide bearing 1-adamantyl group.