Novel chiral thiourea organocatalysts for the catalytic asymmetric oxaziridination
摘要:
Catalytic enantioselective oxaziridination is one of the challenging reactions in the oxidation of organic molecules. In this article, a series of novel chiral thiourea moleculars were synthesized from natural cinchona alkaloids and primary amines. By using these molecules as organocatalysts and m-chloroper-oxybenzoicacid (m-CPBA) as the oxidant, a methodology on highly enantioselective epoxidation of al-dimines has been developed. Several optically active oxaziridines have been constructed in good yields (up to 95%) and moderate to excellent enantioselectivities (up to 99% ee). A plausible transition state was also proposed. (C) 2015 Elsevier Ltd. All rights reserved.
Kinetic Resolution of Oxaziridines via Chiral Bifunctional Guanidine-Catalyzed Enantioselective α-Hydroxylation of β-Keto Esters
作者:Xiaobin Lin、Sai Ruan、Qian Yao、Chengkai Yin、Lili Lin、Xiaoming Feng、Xiaohua Liu
DOI:10.1021/acs.orglett.6b01614
日期:2016.8.5
efficient kinetic resolution of racemic oxaziridines has been realized via catalytic asymmetric α-hydroxylation of available β-ketoesters. In the presence of a chiral bifunctional guanidine catalyst, a variety of optically active oxaziridines and chiral α-hydroxy β-ketoesters were generated with excellent results (ee’s of up to 99% and 97% and yields of up to 44% and 54%, respectively).
Iron-catalyzed kinetic resolution of N-sulfonyl oxaziridines
作者:Kevin S. Williamson、James W. Sawicki、Tehshik P. Yoon
DOI:10.1039/c4sc01371a
日期:——
We have developed a highly selective kinetic resolution of N-sulfonyl oxaziridines. This reaction utilizes an inexpensive and easily synthesized iron bis(oxazoline) catalyst to promote the efficient rearrangement of oxaziridines to the corresponding N-sulfonyl imides; no sacrificial reagents are required to effect this resolution. This process is readily translated to gram scale, which provides a practical method for the preparation of structurally diverse, enantiopure N-sulfonyl oxaziridines for use as reagents in organic synthesis.
Chirality transformation is a basic, attractive, and important strategy for obtaining enantioenriched products with desired chiral elements. The reported chirality conversion reaction often involves the process from one type of chirality to another one. To better utilize the chirality transformation strategy for obtaining two or more products with different chiral elements in a single reaction, a new
Novel chiral thiourea organocatalysts for the catalytic asymmetric oxaziridination
作者:Nan Ji、Jiani Yuan、Shanshan Xue、Junna Zhang、Wei He
DOI:10.1016/j.tet.2015.12.010
日期:2016.1
Catalytic enantioselective oxaziridination is one of the challenging reactions in the oxidation of organic molecules. In this article, a series of novel chiral thiourea moleculars were synthesized from natural cinchona alkaloids and primary amines. By using these molecules as organocatalysts and m-chloroper-oxybenzoicacid (m-CPBA) as the oxidant, a methodology on highly enantioselective epoxidation of al-dimines has been developed. Several optically active oxaziridines have been constructed in good yields (up to 95%) and moderate to excellent enantioselectivities (up to 99% ee). A plausible transition state was also proposed. (C) 2015 Elsevier Ltd. All rights reserved.