α,β-Unsaturated β-Silyl Imide Substrates for Catalytic, Enantioselective Conjugate Additions: A Total Synthesis of (+)-Lactacystin and the Discovery of a New Proteasome Inhibitor
作者:Emily P. Balskus、Eric N. Jacobsen
DOI:10.1021/ja061970a
日期:2006.5.1
Chiral (salen)Al mu-oxo dimer 1 catalyzes the highly enantioselective conjugate addition of carbon-centered nucleophiles to alpha,beta-unsaturated silyl imides. Allyldimethylsilane-substituted imide 4 was identified as an optimal substrate, undergoing addition reactions with a variety of nitrile nucleophiles in high yield and enantiomeric excess. The silicon-containing products are synthetically useful
手性 (salen) Al mu-oxo 二聚体 1 催化碳中心亲核试剂与 α,β-不饱和甲硅烷基酰亚胺的高度对映选择性共轭加成。烯丙基二甲基硅烷取代的酰亚胺 4 被确定为最佳底物,与各种腈亲核试剂以高产率和对映体过量进行加成反应。含硅产品是合成上有用的手性构件,正如它们在强效蛋白酶体抑制剂 (+)-lactacystin (2) 的对映选择性全合成中的应用所证明的。将内酰胺 5a 加工成天然产物分 12 个步骤进行,总产率为 11%,并通过一个不寻常的螺β-内酯中间体 (11) 进行。