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
Chiral Bis(<i>N</i>-arylamino)phosphine-oxazolines: Synthesis and Application in Asymmetric Catalysis
作者:Marc Schönleber、Robert Hilgraf、Andreas Pfaltz
DOI:10.1002/adsc.200800221
日期:2008.9.5
N-alkylation of chiral 1,2-diamines followed by ring closure with phosphorus trichloride (PCl3) and subsequent coupling with an oxazoline alcohol resulted in a new class of N,Pligands. The corresponding iridium tetrakis[3,5-bis(trifluormethyl)phenyl]borate (BArF) complexes were found to be efficient catalysts for the enantioselectivehydrogenation of unfunctionalized olefins and α,β-unsaturated carboxylic
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).
Copper-Catalyzed Asymmetric Allylic Alkylation of Halocrotonates: Efficient Synthesis of Versatile Chiral Multifunctional Building Blocks
作者:Tim den Hartog、Beatriz Maciá、Adriaan J. Minnaard、Ben L. Feringa
DOI:10.1002/adsc.201000109
日期:——
The highly enantioselective synthesis of α‐methyl‐substituted esters is reported in up to 90% yield and up to 99% ee using copper‐TaniaPhos as chiral catalyst. The transformation proved scalable to at least 6.6 mmol (1.7 g scale). The products of this transformation have been further elaborated to multifunctionalbuildingblocks with a single (branched esters and acids) or multiple stereogenic centers
Intrapilosins I−VII, Pentasaccharides from the Seeds of <i>Ipomoea intrapilosa</i>
作者:Moustapha Bah、Lilia Chérigo、Alexandre T. Cardoso Taketa、Mabel Fragoso-Serrano、Gerald B. Hammond、Rogelio Pereda-Miranda
DOI:10.1021/np0701529
日期:2007.7.1
Purification of a CHCl3-soluble extract from seeds of the Mexican medicinal arborescent morningglory, Ipomoea intrapilosa, by means of preparative-scale recycling HPLC, yielded seven new resin glycosides, intrapilosins I-VII (1-7). Their structures were established through the interpretation of their NMR spectroscopic and FABMS data. All pentasaccharides were found to be macrolactones of the known