Abstract
The tricyclic portion 4 of batzelladine B (2) is obtained from 10a, which differs in one side chain from the ptilomycalin A model 10c that we prepared several years ago, by reduction with NaBH3CN in buffered MeOH. Hydrogenation of 11b over at 50 PSI H2 affords the proposed 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 converts 7b to the anti tricyclic acid 15, which is identical to the hydrolysis product of 1. The stereochemistry of the hydrolysis product 15 was confirmed by NOE experiments.