Stereocontrolled synthesis of polyketide libraries: Boron-mediated aldol reactions with aldehydes on solid support
作者:Cesare Gennari、Simona Ceccarelli、Umberto Piarulli、Karim Aboutayab、Monica Donghi、Ian Paterson
DOI:10.1016/s0040-4020(98)00940-5
日期:1998.12
Two complementary classes of chiral boron enolates for adaptation to aldol additions to resin-bound aldehydes were studied: (i) the thioester-derived enolate 1 bearing chiral ligands on boron, and (ii) the chiral ketone-derived enolate 2. The viability of performing highly enantioselective, boron-mediated, aldol reactions was demonstrated by the preparation of resin-bound adducts 15 (91% ee) and 21
研究了两类互补的手性硼烯酸酯,它们适合于醛醇加成到树脂结合的醛上:(i)硫酯衍生的烯酸酯1在硼上带有手性配体,和(ii)手性酮衍生的烯酸酯2。通过制备与树脂结合的加合物15(91%ee)和21(88%ee)可证明进行高对映选择性,硼介导的醛醇缩合反应的可行性。烯醇盐2的固相醛醇缩合反应可以与使用LiBH 4原位还原中间醛缩醛结合,导致有控制地引入四个连续的立体中心,如33→40 (非对映选择性> 96%)。接头的选择至关重要,现有的实验证据表明,三苯甲基和甲硅烷基接头是最佳的。该方法应适合于聚酮化合物文库的立体控制合成。