Free-Radical-Mediated Conjugate Additions. Enantioselective Synthesis of Butyrolactone Natural Products: (−)-Enterolactone, (−)-Arctigenin, (−)-Isoarctigenin, (−)-Nephrosteranic Acid, and (−)-Roccellaric Acid
作者:Mukund P. Sibi、Pingrong Liu、Jianguo Ji、Saumen Hajra、Jian-xie Chen
DOI:10.1021/jo015501x
日期:2002.3.1
alkylation furnished the natural products (-)-enterolactone, (-)-arctigenin, and (-)-isoarctigenin. The overall yields for the target natural products were 20-26% over six steps. Selective functionalization of the disubstituted succinates obtained by aldol condensation gave the paraconic acid natural products (-)-nephrosteranic acid (8) and (-)-roccellaric acid (9). The overall yield of the natural products
路易斯酸介导的烷基向差异保护的富马酸酯10的共轭加成反应产生的单烷基化琥珀酸酯具有很高的化学效率和优异的立体选择性。随后的烷基化或醛醇缩合反应使二取代的琥珀酸酯具有顺式构型。手性助剂4-二苯基甲基-2-恶唑烷酮在两个步骤中控制立体选择性。通过烷基化获得的二取代琥珀酸酯的操作提供了天然产物(-)-内酯,(-)-arctigenin和(-)-异arctigenin。目标天然产物的总产率在六个步骤中为20-26%。通过醛醇缩合获得的二取代琥珀酸酯的选择性官能化得到对苯二酸天然产物(-)-肾甾酸(8)和(-)-二十二烷酸(9)。