ALPHA-HYDROXY ESTERS AS CHIRAL AUXILIARIES IN ASYMMETRIC CYCLOPROPANATIONS BY RHODIUM(II)-STABILIZED VINYLCARBENOIDS
ALPHA-HYDROXY ESTERS AS CHIRAL AUXILIARIES IN ASYMMETRIC CYCLOPROPANATIONS BY RHODIUM(II)-STABILIZED VINYLCARBENOIDS
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DOI：
10.1021/ja00074a012
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发表时间：
1993-10-20
影响因子：
15
通讯作者：
OLIVE, JL
中科院分区：
文献类型：
--
作者：
DAVIES, HML;HUBY, NJS;OLIVE, JL
介绍了几种α -羟基酯作为手性助剂与铑（II）稳定的乙烯基类羰基进行不对称环丙烷化反应。使用(R)-pantolactone或(S)-lactate允许进入这两个系列的对映体乙烯基环丙烷具有可预测的绝对立体化学。手性助剂的位位和电子修饰以及催化剂结构对不对称诱导有重要影响。这些结果是基于手性助剂的羰基氧与类碳之间的相互作用而得到的。通过将不对称环丙烷化与随后的Cope重排相结合，实现了对映选择性进入氢偶氮烯。通过短时间合成(1R,2R)-2-苯基环丙烷氨基酸5，说明了不对称环丙烷化的潜力。
The use of several alpha-hydroxy esters as chiral auxiliaries for asymmetric cyclopropanation with rhodium-(II)-stabilized vinylcarbenoids is presented. Use of either (R)-pantolactone or (S)-lactate allowed entry into both series of enantiomeric vinylcyclopropanes with predictable absolute stereochemistry. Steric and electronic modifications of the chiral auxiliary as well as catalyst structure were shown to have major effects on the asymmetric induction. These results were rationalized on the basis of an interaction between the carbonyl oxygen of the chiral auxiliary and the carbenoid carbon. By combining the asymmetric cyclopropanation with a subsequent Cope rearrangement, an enantioselective entry into hydroazulenes was achieved. The potential of the asymmetric cyclopropanation was illustrated by a short synthesis of (1R,2R)-2-phenylcyclopropane amino acid 5.