On the reactivity of 23-methoxycarbonyl furospirostanes
摘要:
Bronsted and Lewis acid-catalysed reactions of the 23-methoxycarbonyl furospirostanic side chain are described. While bromination, deuteration and BF3 center dot Et2O/AcOH treatment involve regioselective F-ring opening with exclusive participation of Delta(22)-furostenic intermediates, BF3 center dot Et2O/Ac2O treatment leads to irreversible E- or F-ring cleavage. (C) 2011 Elsevier Inc. All rights reserved.