The condensation of β-cyclocitral (4); with 3-isopropyl-4-methoxybenzyl chloride (5) in the presence of lithium naphthalenide gave an alcohol (6), which was then oxidized to the corresponding α,β-unsaturated ketone (7). The Intramolecular cyclization of 7 with polyphosphoric acid yielded (±)-12-methoxyabieta-8,11,13-trien-6-one (8) and its cis-isomer (9), which was then successfully converted into
β-环
柠檬醛(4)的缩合;在
萘化
锂存在下与 3-异丙基-4-甲氧基苄基
氯 (5) 反应得到醇 (6),然后将其氧化为相应的 α,β-不饱和酮 (7)。7 与多
磷酸的分子内环化产生 (±)-12-methoxyabieta-8,11,13-trien-6-one (8) 及其顺式异构体 (9),然后通过烯醇成功转化为 8
醋酸盐 (11)。8酮用
三溴化硼去甲基化得到
苯酚(18),然后用
氢化铝锂还原得到相应的醇(19)。用
过氧化苯甲酰将 19 中的 C-11 位氧化得到 (±)-12-benzoyloxyabieta-8,11,13-trien-6β,11-diol (20),它用
氢化铝锂还原并随后氧化用琼斯试剂,得到 (±)-紫杉二酮 (1)。