Reactivity and enantioselectivity in the reactions of scalemic stereogenic α-(N-carbamoyl)alkylcuprates

被引:63
作者
Dieter, RK [1 ]
Oba, G [1 ]
Chandupatla, KR [1 ]
Topping, CM [1 ]
Lu, K [1 ]
Watson, RT [1 ]
机构
[1] Clemson Univ, Dept Chem, Howard L Hunter Chem Lab, Clemson, SC 29634 USA
关键词
D O I
10.1021/jo035845i
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
Stereogenic 2-(N-carbamoyl)pyrrolidinylcuprates prepared from scalemic (i.e., enantioenriched) N-Boc-2-lithiopyrrolidine and THF soluble CuCN(.)2LiCl react with vinyl iodides, vinyl triflates, beta-iodo-alpha,beta-enoates, propargyl mesylates, and allyl bromide to afford the substitution products with excellent enantioselectivity. Excellent enantiomeric ratios are obtained in the conjugate addition reactions with methyl vinyl ketone while low enantiomeric ratios can be achieved with acrylate esters using HMPA/TMSCl activation. Enantiomeric ratios vary with substrate substitution patterns and the observed enantioselectivities appear to be more a function of cuprate-electrophile reactivities than of the reaction type (e.g., substitution, conjugate addition). Low enantiomeric ratios are obtained with the alpha-(N-carbamoyl)benzylcuprates. The lithium-copper transmetalation and cuprate vinylation reactions proceed with retention of configuration.
引用
收藏
页码:3076 / 3086
页数:11
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