Concise, Enantioselective, and Versatile Synthesis of (−)-Englerin A Based on a Platinum-Catalyzed [4C+3C] Cycloaddition of Allenedienes
作者:Ronald Nelson、Moisés Gulías、José L. Mascareñas、Fernando López
DOI:10.1002/anie.201607348
日期:2016.11.7
A practical synthesis of (−)‐englerin A was accomplished in 17 steps and 11 % global yield from commercially available achiral precursors. The key step consists of a platinum‐catalyzed [4C+3C] allenediene cycloaddition that directly delivers the trans‐fused guaiane skeleton with complete diastereoselectivity. The high enantioselectivity (99 % ee) stems from an asymmetric ruthenium‐catalyzed transfer
(-)-恩格尔林A的实用合成过程由市售的非手性前体完成,共分17个步骤完成,全球收率为11%。关键步骤包括铂催化的[4C + 3C]烯丙二烯环加成反应,该加成反应可直接提供具有完全非对映选择性的反式愈创木瓜骨架。高对映选择性(99% ee)源自易于组装的二烯-炔酮的不对称钌催化的转移加氢。该合成还具有高度立体选择性的氧合作用和后期的铜酸盐烷基化作用,可制备以前难以获得的结构类似物。