SYNTHESIS OF THE TRICYCLIC PORTIONS OF BATZELLADINE-A, BATZELLADINE-BAND BATZELLADINE-D - REVISION OF THE STEREOCHEMISTRY OF BATZELLADINE-A AND BATZELLADINE-D

The tricyclic portion 4 of batzelladine B (2) is obtained from 10a, wh ich differs in one side chain from the ptitomycalin A model 10c that w e prepared several years ago, by reduction with NaBH3CN in buffered Me OH. Hydrogenation of 11b over Rh/Al2O3 at 50 PSI H-2 affords the propo sed tricyclic portion 12b of batzelladine A (1). Epimerization of 12b and hydrolysis affords acid 3, which is similar to, but different from , the acid obtained from hydrolysis of 1. A five step sequence convert s 7b to the anti tricyclic acid 15, which is identical to the hydrolys is product of 1. The stereochemistry of the hydrolysis product 15 was confirmed by NOE experiments. Copyright (C) 1996 Elsevier Science Ltd