predominant aldol adduct, syn-9, was transformed into gamma,delta-epoxy allylic alcohol 8 by a nine-step sequence, including the substrate-controlled 1,2-reduction of enone, syn-12, also the epoxidation of allylic alcohol 15. Epoxy-alcohol 8 underwent 5-exo-cyclization in a high regioselective manner under acidic conditions to produce a bicyclic key intermediate (+)-7, which was eventually efficiently
天然(+)-cheimonophyllon E(5)和(+)-cheimonophyllal(6)的高度对映体控制的总合成已完成,这在
生物学上引起了人们的兴趣,它是氧化的Bisabolane型
倍半萜类
生物。本合成策略的特征在于使用不对称醛醇型反应在第一步合成步骤中制备旋光的6-C-取代的3-甲基-2-
环己烯酮衍
生物。因此,在手性(酰氧基)
硼烷(
CAB)型山本催化剂33存在下,1-甲基-3-甲
硅烷氧基-
1,3-环己二烯31与α,β-不饱和醛11的Mukaiyama羟醛反应进行得很高。非对映选择性和对映选择性的
水平。通过九步序列将主要的醛醇加合物syn-9转化为γ-δ-环氧
烯丙醇8,包括底物控制的烯酮syn-12的1,2-还原,