Asymmetric Hydrogenation Routes to Deoxypolyketide Chirons
作者:Jianguang Zhou、James W. Ogle、Yubo Fan、Vorawit Banphavichit(Bee)、Ye Zhu、Kevin Burgess
DOI:10.1002/chem.200700390
日期:2007.8.27
selectivity; this is the first time this has been achieved in any asymmetric synthesis of a deoxypolyketide fragment. Throughout, diastereoselectivities of the crude material in the syntheses of alpha,omega-functionalized internal deoxypolyketide fragments were in excess of 11:1.0 and chromatographically purified samples could be isolated in high yields with dr (dr=diastereomeric ratio) values consistently
Highly Enantioselective Iridium-Catalyzed Hydrogenation of α,β-Unsaturated Esters
作者:Jia-Qi Li、Xu Quan、Pher G. Andersson
DOI:10.1002/chem.201200907
日期:2012.8.20
α,β‐Unsaturated esters have been employed as substrates in iridium‐catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic‐ and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural
METHOD FOR PRODUCING a-SUBSTITUTED CYSTEINE OR SALT THEREOF OR SYNTHETIC INTERMEDIATE OF a-SUBSTITUTED CYSTEINE
申请人:API Corporation
公开号:US20160083341A1
公开(公告)日:2016-03-24
According to the present invention, it becomes possible to perform a process for converting into an α-substituted cysteine represented by general formula (1) or a salt thereof at low cost and on an industrial scale by employing a process that is routed through a compound represented by general formula (3) to a compound represented by general formula (6). Particularly, by employing a process that is routed through a compound represented by general formula (7-2), it becomes possible to detach a tert-butyl protection group in a simple manner and to produce the compound represented by general formula (1) with high purity. Furthermore, by employing a process that is routed through tert-butylthiomethanol or a process that is routed through a compound represented by general formula (9), it becomes possible to produce a compound represented by general formula (2) without generating bischloromethylether that is an oncogenic substance. In the production of an α-substituted-D-cysteine or a salt thereof, it becomes possible to perform a process for converting the compound represented by general formula (2) into a compound represented by general formula (3S) in one step by allowing an enzyme or the like to act on the compound represented by general formula (2).
An improved method is described for making single isomers of synthetic benzoprostacyclin analogue compounds, in particular the pharmacologically active 314-d isomer of beraprost. In contrast to the prior art, the method is stereoselective and requires fewer steps than the known methods for making these compounds.
A Comparison between Oxazoline-imidazolinylidene, -imidazolylidine, -benzimidazolylidene Hydrogenation Catalysts
作者:Sakunchai Khumsubdee、Yubo Fan、Kevin Burgess
DOI:10.1021/jo4013783
日期:2013.10.4
benzimidazolylidene complexes 1a–c were prepared and tested in asymmetrichydrogenations of a series of largelyunfunctionalizedalkenes. Similarities and differences in the catalytic performance of these complexes were rationalized in terms of the predicted mechanisms of these reactions, and their relative tendencies to generate protons under the hydrogenation conditions.