Synthesis of 14 beta-cholesta-5,7-dien-3 beta-ol

New oxidized sterols from Aspergillus awamori and the endo-boat conformation adopted by the cyclohexene oxide system

Two new oxidized sterols 1 and 2 were obtained from the active fraction of a mangrove fungus Aspergillus awamori isolated from the soils around the mangrove plant Acrostichum speciosum. Their structures were elucidated using spectroscopic methods as 22E-7alpha-methoxy-5alpha,6alpha-epoxyergosta-8(14),22-dien-3beta-ol (1) and 22E-3beta-hydroxy-5alpha,6alpha,8alpha,14alpha-diepoxyergosta-22-en-7-one (2). The NMR data and complete assignments for both DMSO-d(6) and CDCl(3) were given. Their cytotoxic activity against A549 cell line was evaluated. Furthermore, the detailed conformation analysis for ring B (cyclohexene oxide system) of sterol 1 was given on the basis of NOEs. The endo-boat conformation was considered as the preferred conformation for ring B rather than half-chair conformation.

Hydroboration of 5 alpha-ergost-8-en-3 beta-ol

Hydration via hydroboration of 5 alpha-ergost-8-en-3 beta-ol affords 5 alpha-ergostane-3 beta, 15 alpha-diol, 5 alpha, 14 beta-ergostane-3 beta, 15 beta-diol, and 5 alpha-ergostane-3 beta, 7 beta-diol, and not 5 alpha, 9 beta-ergostane-3 beta, 7 beta-diol, as previously reported by others.