Highly enantioselective cyclopropanation of styrenes and diazoacetates catalyzed by 3-oxobutylideneaminatocobalt(II) complexes, Part 1. Designs of cobalt complex catalysts and the effects of donating ligands
Highly enantioselective cyclopropanation of styrenes and diazoacetates catalyzed by 3-oxobutylideneaminatocobalt(II) complexes, Part 1. Designs of cobalt complex catalysts and the effects of donating ligands
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DOI：
10.1246/bcsj.74.2139
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发表时间：
2001-11-01
影响因子：
4
通讯作者：
Yamada, T
中科院分区：
文献类型：
--
作者：
Ikeno, T;Sato, M;Yamada, T
合理设计的3-氧代亚丁基氨基钴(II)配合物有效地催化了苯乙烯衍生物和重氮乙酸酯的高对映选择性环丙烷化反应，其配体由1,2-二甲基乙二胺和3-氧代丁酸烷基酯制备。配合物二胺单元的空间需求严重影响了对映选择性，侧链上的酯基在一定程度上提高了反式选择性。添加催化量的 N-甲基咪唑显着加速了反应并增强了对映选择性，因为它作为轴向配体与配合物的中心钴原子配位。醇类或水性醇类溶剂对于 1-取代的 1-苯基乙烯的环丙烷化也特别有效，可在甲醇水溶液中实现高对映选择性。
Highly enantioselective cyclopropanation of styrene derivatives and diazoacetates was effectively catalyzed by reasonably designed 3-oxobutylideneaminatocobalt(II) complexes, whose ligands were prepared from 1,2-dimesitylethylenediamine and alkyl 3-oxobutanoates. The steric demand of the diamine unit of the complexes seriously influenced the enantioselectivity, and the ester groups on their side chains somewhat improved the trans-selectivity. Addition of a catalytic amount of N-methylimidazole significantly accelerated the reaction and enhanced the enantioselectivity due to its coordination to the center cobalt atom of the complex as an axial ligand. Alcoholic or aqueous alcoholic solvents were also effective particularly for the cyclopropanation of 1-substituted 1-phenylethylenes to achieve high enantioselectivity in aqueous methanol.