Manganese η2-Complexes as Auxiliaries for Stereoselective Aldol Synthesis of Allenyl Carbinols
Manganese η2-Complexes as Auxiliaries for Stereoselective Aldol Synthesis of Allenyl Carbinols
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DOI：
10.1021/ol1021096
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发表时间：
2010-11-05
期刊：
影响因子：
5.2
通讯作者：
Lepore, Salvatore D.
中科院分区：
文献类型：
--
作者：
Bhowmick, Manishabrata;Lepore, Salvatore D.
通过ETA(2)-键与甲基环戊二烯基锰的三羰基进行温和的络合反应，将一种方便而坚固的锰助剂连接到了炔基酯和酮上。该络合物很容易发生Aldol反应，并且具有良好的非对映选择性，特别是与芳基酮底物的Aldol反应。用循环过渡态模型对这种选择性进行了合理化，在循环过渡态模型中，锰助剂在促进累积柳酸酯中间体的E(O)几何构型方面起到了关键作用。
A convenient and robust manganese auxiliary was linked via an eta(2)-bond to alkynyl esters and ketones using a mild complexation reaction with methylcyclopentadienyl manganese tricarbonyl. This complex readily underwent aldol reactions with exclusive alpha-substitution and in good diastereoselectivities especially with aryl ketone substrates. This selectivity has been rationalized using a cyclic transition state model in which the manganese auxiliary plays a critical role in promoting E(O)-geometry of the cumulenolate intermediate.