Hetisine derivatives. Part 1. Acetylation and oxidation of hetisine

Abstract

Acetylation of hetisine (1) under drastic conditions afforded 2-acetyl (8), 11-acetyl (9), 13-acetyl (5), 2,11-diacetyl (7), 11,13-diacetyl (2) and 2,11,13-triacetyl (6) hetisines. Sarett oxidation of the compounds (9), (5), (7) and (2) gave 11-acetyl-2,13-didehydro (11), 13-acetyl-2,11-didehydro (12), 13-dehydro-2,11-diacetyl (14) and 2-dehydro-11,13-diacetyl (10) hetisines, respectivsly. Alkaline hydrolysis of (12) and (8) gave 2,11-didehydrohetisine (13) and 2-dehydrohetisine (hetisinone) (3), respectively. Sarett oxidation of hetisine (1) afforded (13) as the major product besides 11-dahylrohetisine (15). All the compounds have been characterized by their ir, ms, ¹H nmr and ¹³H nmr data. The location of keto groups in the hetisine derivatives (3), (10), (11), (12), (13), (14) and (15) has been confirmed by CD and ORD meaeurements.