Practical Pd(II)-Catalyzed C-H Alkylation with Epoxides: One-Step Syntheses of 3,4-Dihydroisocoumarins
Practical Pd(II)-Catalyzed C-H Alkylation with Epoxides: One-Step Syntheses of 3,4-Dihydroisocoumarins
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DOI：
10.1021/jacs.5b07507
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发表时间：
2015-09-02
影响因子：
15
通讯作者：
Yu, Jin-Quan
中科院分区：
文献类型：
--
作者：
Cheng, Guolin;Li, Tuan-Jie;Yu, Jin-Quan
Pd（II）催化的苯甲酸与末端和内部环氧化物的邻位烷基化一步得到3，4-二氢异香豆素。钾抗衡阳离子的存在对该反应至关重要。单保护的氨基酸配体显著促进该反应，使得能够开发使用0.5摩尔% Pd催化剂的实用C-H烷基化反应。C-H烷基化步骤中立体化学的反转与氧化还原中性S（N）2亲核开环过程一致，而不是Pd（II）/Pd（IV）途径。
Pd(II)-catalyzed ortho-alkylation of benzoic acids with both terminal and internal epoxides affords 3,4-dihydroisocoumarins in one step. The presence of potassium countercations is crucial for this reaction. Monoprotected amino acid ligands significantly promote this reaction, enabling the development of a practical C-H alkylation reaction using 0.5 mol % Pd catalyst. The inversion of stereochemistry in the C-H alkylation step is consistent with a redox-neutral S(N)2 nucleophilic ring-opening process as opposed to a Pd(II)/Pd(IV) pathway.