Total Synthesis of (−)-Citreoisocoumarin, (−)-Citreoisocoumarinol, (−)-12-<i>epi</i>-Citreoisocoumarinol, and (−)-Mucorisocoumarins A and B Using a Gold(I)-Catalyzed Cyclization Strategy
作者:N. Arjunreddy Mallampudi、Utkal Mani Choudhury、Debendra K. Mohapatra
DOI:10.1021/acs.joc.9b03278
日期:2020.3.20
the common intermediate 1. Central to the synthetic approach is a regioselective gold(I)-catalyzed 6-endo-dig cyclization strategy for the construction of isocoumarin skeleton. The other key steps in this approach included Sonogashira coupling, Tsuji-Wacker oxidation, Evans-Saksena's 1,3-anti-reduction and Narasaka-Prasad's 1,3-syn-reduction. The synthetic results unambiguously confirmed the absolute
(-)-邻甲基异香豆素(2),(-)-邻甲基异香豆素(3),12-表-异异香豆素(4),(-)-异皮质香豆素A(5)和B(6)的统一简洁的第一不对称全合成。已从通用中间体1完成。合成方法的中心是区域选择性金(I)催化的6-内切-挖掘环化策略,用于构建异香豆素骨架。该方法的其他关键步骤包括Sonogashira偶联,Tsuji-Wacker氧化,Evans-Saksena的1,3-抗还原和Narasaka-Prasad的1,3-syn还原。合成结果清楚地证实了天然产物黏膜异香豆素A和B在C-10和C-12处的绝对立体化学分别为(-)-(10R,12S)-5和(+)-(10S,12S)-6 。