Steroids. Part VIII. Cholesta-1,3,5-trien-7-one and its dimer

Abstract

Bromination of cholesta-3,5-dien-7-one with N-bromosuccinimide yields mainly the 2β-bromo-derivative, with small amounts of 8-bromo- and 2,8-dibromo-derivatives. Dehydrobromination of 2β-bromocholesta-3,5-dien-7-one gives cholesta-1,3,5-trien-7-one the identification of which is confirmed by the preparation of a tricarbonyliron(O) complex and by n.m.r. spectroscopy. When the trienone is heated above its melting point it forms a Diels–Alder dimer.