(±)-19-去甲基-4(18),8,11,13-四烯-松香烷-7-酮的全合成

Total Synthesis of (±)-19-Norabieta-4(18),8,11,13-tetraen-7-one

以间异丙基溴苯 1为起始原料 ,通过进攻环氧乙烷及溴代两步制得溴化物 3.溴化物 3与 Hagemann′s酯发生偶联反应 ,水解后生成偶联产物 5 .再以路易斯酸 BF3 ·Et2 O催化化合物 5进行分子内环化为关键步骤得到反式稠合中间体 6 ,最后通过与三苯基膦碘甲烷季盐发生 Wittig反应及氧化 ,合成了 (± ) -1 9-去甲基 -4 (1 8) ,8,1 1 ,1 3-四烯 -松香烷 -7-酮 [1 9-nor-abieta-4 (1 8) ,8,1 1 ,1 3-tetraen-7-one](8) .

?-19-Norabieta-4(18),8,11,13-tetraen-7-one(8) was first synthesized starting from m-isopropylbromobenzene(1). After bromination of alcohol(2), coupling reaction of bromide(3) with Hagemann′s ester in the presence of t-BuOK and hydrolysis of compound(4) with KOH, compound (5) was obtained in a high yield. Intramolecular cyclization of coupling compound(5) with BF 3·Et 2O afforded a trans-fused key intermediate(6). After structural modification by Wittig reaction with Ph 3P +CH 3I - and oxidation with CrO 3, the target molecule was obtained in a good yield.