Author's Organization：Takamine Research Laboratory and Shinagawa Plant, Sankyo Co., Ltd. Takamine Research Laboratory and Shinagawa Plant, Sankyo Co., Ltd.
Bromination of cholesta-3, 5-dien-7-one (I) with N-bromosuccinimide afforded 2-bromocholesta-3, 5-dien-7-one (II) and dehydrobromination of (II) yielded cholesta-1, 3, 5-trien-7-one (III), whose structure was established by leading it to the maleic anhydride adduct (VII) and hydrogenation.
