作者:Dieter Enders、Anja Kaiser
DOI:10.1055/s-1996-4195
日期:1996.2
(+)-Ramulosin, a metabolite of Pestalotia ramulosa, and its enantiomer have been synthesized in high enantiomeric purity (ee ≥ 98%) via Michael addition of metalated acetone SAMP-hydrazone (S)-1a to the acetal protected cyclic enoate 2 and subsequent diastereoselective reductive lactonization with L-Selectride. 3-Substituted hexahydroisocoumarines (3S,4aR)-5, analogues of ramulosin, were also obtained with excellent stereoselectivities (de ≥ 98%, ee ≥ 96%) using this method.
(通过将金属化丙酮 SAMP- 酰腙 (S)-1a 与受乙缩醛保护的环状烯酸酯 2 迈克尔加成,并随后与 L-选择性化合物进行非对映选择性还原内酯化,合成了对映体纯度极高的 (+)-Ramulosin 及其对映体(ee ≥ 98%)。用这种方法还得到了 3-取代的六氢异香豆素 (3S,4aR)-5,这是雷公藤素的类似物,具有极好的立体选择性(de ≥ 98%,ee ≥ 96%)。