钯催化烯丙基取代反应中手性配体的“甲基效应”  

The "Methyl Effect" in The Enantioselective Allylic Substitution Using Palladium/Chiral Pyridinylmethyl-oxazolines

作　　者：李枝蓬[1] 汤方毅[1] 伍新燕[1] 周其林[1] 陈新滋[2] 

机构地区：[1]华东理工大学精细化工研究所,上海200237 [2]香港理工大学应用生物与化学工程系

出　　处：《高等学校化学学报》2001年第12期2032-2033,共2页Chemical Journal of Chinese Universities

基　　金：国家重点基础研究发展规划项目基金 (编号 :G2 0 0 0 0 775 0 6 );国家自然科学基金 (批准号 :2 9972 0 2 7);香港理工大学ASD基金资助

摘　　要：In this paper, two types of chiral ligands 1 and 2 containing pyridinyl moiety and oxazolines bridged by a methylene group were investigated in the palladium catalyzed substitution of 1,3 diphenyl 2 propenyl acetate with dimethyl malonate. Ligands 2, which have two methyl groups at the bridged methylene, gave higher enantioselectivities than their unsubstituted analogues 1. This "methyl effect" increased while the substituent on the C 4 in the oxazoline ring was changed from benzyl to tert butyl. Despite of that the "methyl effect" was found in the palladium catalyzed enantioselective allylic substitution, it was obviously significant for assisting rational design of chiral ligands and catalysts in other asymmetric reaction.In this paper, two types of chiral ligands 1 and 2 containing pyridinyl moiety and oxazolines bridged by a methylene group were investigated in the palladium catalyzed substitution of 1,3 diphenyl 2 propenyl acetate with dimethyl malonate. Ligands 2, which have two methyl groups at the bridged methylene, gave higher enantioselectivities than their unsubstituted analogues 1. This 'methyl effect' increased while the substituent on the C 4 in the oxazoline ring was changed from benzyl to tert butyl. Despite of that the 'methyl effect' was found in the palladium catalyzed enantioselective allylic substitution, it was obviously significant for assisting rational design of chiral ligands and catalysts in other asymmetric reaction.

关 键 词：不对称催化 烯丙基取代反应 手性吡啶恶唑啉配体 甲基效应 有机合成 

分 类 号：O621.36[理学—有机化学] O621.251[理学—化学]