Three different routes to the hexahydroazepine unit of the natural products balanol (1) and ophiocordin (2) are described. The common starting material is the chiral epoxy alcohol 3 which is converted to the balanol degradation product 10 (Scheme 1) or to suitably protected derivatives thereof: 15 (Scheme 2) and 19 (Scheme 3). A key step in the first route is the acid-catalysed ring-opening of bicyclic
描述了三种不同的
天然产物Balanol(1)和ophiocordin(2)通往六氢氮杂unit单元的途径。常见的起始原料是手性环氧醇3,其被转化为Balanol降解产物10(方案1)或其适当保护的衍
生物:15(方案2)和19(方案3)。第一条途径中的关键步骤是双环
氮丙啶8的酸催化开环,其
化学收率高(分离出71%),并且具有显着的区域选择性(98:2有利于所需的区域异构体)。