基于手性助剂的芳基重氮乙酸酯和手性双铑催化剂介导的苄基硅醚的不对称分子间C-H官能化反应
Asymmetric intermolecular C-H functionalization of benzyl silyl ethers mediated by chiral auxiliary-based aryldiazoacetates and chiral dirhodium catalysts.
作者信息
Davies Huw M L, Hedley Simon J, Bohall Brooks R
机构信息
Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260-3000, USA.
出版信息
J Org Chem. 2005 Dec 23;70(26):10737-42. doi: 10.1021/jo051747g.
[reaction: see text] C-H functionalization of benzyl silyl ethers by means of rhodium-catalyzed insertions of aryldiazoacetates can be achieved in a highly diastereoselective and enantioselective manner by judicious choice of chiral catalyst or auxiliary. The dirhodium tetraprolinates such as Rh2((S)-DOSP)4 have been widely successful as chiral catalysts in the C-H functionalization chemistry of aryldiazoacetates, but give poor enantioselectivity in the reactions of aryldiazoacetates with benzyl silyl ether derivatives. The use of (S)-lactate as a chiral auxiliary resulted in C-H functionalization with moderately high diastereoselectivity (79-88% de) and enantioselectivity (68-85% ee). The best results (91-95% de, 95-98% ee), however, were achieved using Hashimoto's Rh2((S)-PTTL)4 catalyst.
[反应：见正文] 通过明智地选择手性催化剂或助剂，借助铑催化的芳基重氮乙酸酯插入反应，苄基硅醚的C-H官能化可以以高度非对映选择性和对映选择性的方式实现。诸如Rh2((S)-DOSP)4之类的四脯氨酸二铑在芳基重氮乙酸酯的C-H官能化化学中作为手性催化剂已广泛取得成功，但在芳基重氮乙酸酯与苄基硅醚衍生物的反应中对映选择性较差。使用(S)-乳酸作为手性助剂导致C-H官能化具有中等较高的非对映选择性（79 - 88%的非对映体过量）和对映选择性（68 - 85%的对映体过量）。然而，使用桥本的Rh2((S)-PTTL)4催化剂可获得最佳结果（91 - 95%的非对映体过量，95 - 98%的对映体过量）。
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