The synthesis of two isomeric brassinosteroids, analogues of brassinolide,
containing the 2 beta,3 beta diol system typical of ecdysteroids and a five
-membered lactone bonded to the steroid ring B is described. The synthesis
leads to both lactones via a metal hydride reduction of the Diels-Alder add
uct of ergosterol. (C) 1999 Elsevier Science Ltd. All rights reserved.