Enantioselective synthesis and stereoselective rearrangements of enol ester epoxides.
Enantioselective synthesis and stereoselective rearrangements of enol ester epoxides.
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烯醇酯环氧化物的对映选择性合成和立体选择性重排。
DOI：
10.1021/jo001593z
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发表时间：
2001
期刊：
影响因子：
--
通讯作者：
Shi,Y
中科院分区：
文献类型：
--
作者：
Zhu,Y;Shu,L;Tu,Y;Shi,Y
以果糖衍生的手性酮为催化剂，氧酮为氧化剂，烯醇酯具有较高的对映选择性。对对映体富集的烯醇酯环氧化物的详细研究表明，酸催化的重排可以通过两种不同的途径进行，一种是构型保留，另一种是反转。这两种途径之间的竞争高度依赖于酸性催化剂的性质。强酸有利于构型的保持，弱酸有利于构型的反转。在热条件下，这些环氧化物具有高度立体选择性重排和构型反转。通过合理选择反应条件，烯醇酯环氧化物的一个对映体可以生成α-酰基酮的任意一个对映体。
Enol esters can be epoxidized with high enantioselectivities using the fructose-derived chiral ketone1as catalyst and Oxone as oxidant. A detailed study of enantiomerically enriched enol ester epoxides has revealed that the acid-catalyzed rearrangement can proceed through two distinct pathways, one with retention of configuration and the other with inversion. The competition between the two pathways is highly dependent upon the nature of the acid catalyst. A strong acid favors retention of configuration and a weak acid favors inversion of configuration. Under thermal conditions, these epoxides rearrange highly stereoselectively with inversion of configuration. Either enantiomer of an α-acyloxy ketone can be formed from one enantiomer of an enol ester epoxide by judicious choice of reaction conditions.