Enantioselective Cross-Coupling of <i>meso</i>-Epoxides with Aryl Halides
作者:Yang Zhao、Daniel J. Weix
DOI:10.1021/jacs.5b01909
日期:2015.3.11
The first enantioselective cross-electrophile coupling of aryl bromides with meso-epoxides to form trans-β-arylcycloalkanols is presented. The reaction is catalyzed by a combination of (bpy)NiCl2 and a chiral titanocene under reducing conditions. Yields range from 57 to 99% with 78–95% enantiomeric excess. The 30 examples include a variety of functional groups (ether, ester, ketone, nitrile, ketal
Optically active trans-2-aryl-1-cyclohexanol derivatives and a process
申请人:Chisso Corporation
公开号:US05395766A1
公开(公告)日:1995-03-07
The present invention provides an optically active trans-2-aryl-1-cyclohexanol derivative represented by the following general formula (I). ##STR1## The compounds can be obtained by transesterifiation reaction of the following compound (II) as a starting material with lipase. ##STR2## The optically active trans-2-aryl-1-cyclohexanol derivative can be used as an asymmetric source of asymmetric Diels-Alder reaction or a starting material of physiological active materials.
Diastereoselective and Enantioselective Silylation of 2-Arylcyclohexanols
作者:Li Wang、Ravish K. Akhani、Sheryl L. Wiskur
DOI:10.1021/acs.orglett.5b00919
日期:2015.5.15
The silylation-based kinetic resolution of trans 2-arylcyclohexanols was accomplished by employing a triaryl silyl chloride as the derivatizing reagent with a commercially available isothiourea catalyst. The methodology is selective for the trans diastereomer over the cis, which provides an opportunity to selectively derivatize one stereoisomer out of a mixture of four. By employing this technology, a facile, convenient method to form a highly enantiomerically enriched silylated alcohol was accomplished through a one-pot reduction-silylation sequence that started with a 2-aryl-substituted ketone.
Regioselective ring-opening of epoxides with ortho-lithioanisoles catalyzed by BF3·OEt2
作者:Erkan Ertürk、Mustafa A. Tezeren、Taner Atalar、Tahir Tilki
DOI:10.1016/j.tet.2012.05.116
日期:2012.8
It is presented that a number of o-2-hydroxyalkylanisoles could be efficiently synthesized through the regioselective ring-opening reaction of epoxides with o-lithioanisoles in the presence of BF3 center dot OEt2 Lewis-acid catalyst. Sterically demanding o-lithioanisoles had to be generated by exploiting the combination of (BuLi)-Bu-n and a catalytic amount of TMEDA (0.20 equiv) in Et2O as the lithiator whereas 'normal' anisole could be lithiated at ortho-position by treatment with (BuLi)-Bu-n in THE as usual. Surprisingly, the availability of THE and a catalytic amount of TMEDA (0.20 equiv) in the reaction mixture was found to enhance the reaction yields dramatically. A complex aggregate formation by the co-operative ligation of THF and TMEDA to ortho-lithioanisole(s) was proposed to rationalize the high reactivity achieved in the ring-opening reaction of epoxides. (C) 2012 Elsevier Ltd. All rights reserved.