对映选择合成
环丙烷化
迈克尔反应
多米诺骨牌
烷基化
有机催化
催化作用
化学
有机化学
组合化学
作者
Ismail Ibrahem,Gui‐Ling Zhao,Ramón Rios,Ján Veselý,Henrik Sundén,Pawel Dziedzic,Armando Córdova
标识
DOI:10.1002/chem.200800442
摘要
Abstract The development of one‐pot organocatalytic domino Michael/α‐alkylation reactions between bromomalonates or bromoacetoacetate esters and α,β‐unsaturated aldehydes is presented. The chiral‐amine‐catalyzed reactions with bromomalonates as substrates give access to the corresponding 2‐formylcyclopropane derivatives in high yields with excellent diastereoselectivity and up to 99 % ee . The catalytic domino Michael/α‐alkylation reactions between 4‐bromo‐acetoacetate and enals provide a route for the synthesis of functionalized cyclopentanones in good to high yields with 93–99 % ee . The products from the organocatalytic reactions were also reduced with high diastereoselectivity to the corresponding cyclopropanols and cyclopentanols, respectively. Moreover, one‐pot combinations of amine and heterocyclic carbene catalysis (AHCC) enabled the highly enantioselective synthesis of β‐malonate esters (91–97 % ee ) from the reaction between bromomalonates and enals. The tandem catalysis included the catalytic domino reaction followed by catalytic in situ chemoselective ring‐opening of the 2‐formylcyclopropane intermediates.
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