Intramolecular functionalization of N-cyanamide radicals: synthesis of 1,4-and 1,5-N-cyanoepimino compounds

Abstract

Photolysis of 3β-methoxymethoxy-5α-cholestan-6β-ylcyanamide (6), 29-methoxyfriedelan-3β-yl-cyanamide (15), (22R,25R)-5α-furostan-26-ylcyanamide (23), 8α,12-(12R/12S)-epoxylabdan-15-ylcyanamides, (32) and (33), in the presence of iodine and lead tetra-acetate leads to neutral cyanimyl radicals which undergo intramolecular hydrogen abstraction to produce N-cyanoepimino compounds. Better results are obtained with the system iodine and diacetoxyiodobenzene. The starting cyanamides have been prepared by reduction of the oximes (3) and (13) and of the amides (20), (28), and (29), respectively, with lithium aluminium hydride followed by cyanation with cyanogen bromide or with sodium cyanate and subsequent dehydration of the urea derivative with methanesulphonyl chloride.