Enantioselective iridium-catalyzed allylic substitution with a Reformatsky reagent: direct construction of β-stereogenic homoallylic esters  

作　　者：Debasis Pal Kirana DVeeranna Yuk Fai Wong PAndrew Evans 

机构地区：[1]Department of Chemistry,Queen’s University,90 Bader Lane,KingstonK7L 3N6,Canada [2]Xiangya School of Pharmaceutical Sciences,Central South University,Changsha410013,China

出　　处：《Science China Chemistry》2024年第11期3791-3797,共7页中国科学（化学英文版）

基　　金：the National Sciences and Engineering Research Council (NSERC) for a Discovery Grant;supporting a Tier 1 Canada Research Chair (P.A.E);the Huxiang High-Level Talent Gathering Project from the Science and Technology Department of Hunan Province (Grant No. 2020RC5001)。

摘　　要：The Reformatsky reagent derived from ethyl bromoacetate circumvents the challenge associated with the direct regio-and enantioselective iridium-catalyzed allylic alkylation with an unstabilized aliphatic ester enolate. Notably, this work represents the first example of using a Reformatsky reagent in a metal-allyl reaction, which permits the direct construction of enantioenriched β-stereogenic homoallylic esters without preactivation of the pronucleophile or post-reaction modification of the product(e.g., thermal decarboxylation of a 1,3-dicarbonyl). Moreover, the process allows the coupling of a broad range of sterically and electronically diverse electrophiles bearing aryl, heteroaryl and alkenyl derivatives, including the significantly more challenging alkyl-substituted allylic carbonates. The versatility of the ester product is exemplified by a series of functional group manipulations and the development of a concise and efficient enantioselective total synthesis of the natural product,(+)-descurainolide A. Finally, mechanistic studies indicate that the zinc enolate behaves as a soft nucleophile that undergoes outer-sphere alkylation.

关 键 词：allylic substitution asymmetric catalysis mechanistic studies natural product synthesis Reformatsky reagent 

分 类 号：O621.251[理学—有机化学]