Metal-Free Catalytic Boration at the β-Position of α,β-Unsaturated Compounds: A Challenging Asymmetric Induction
作者:Amadeu Bonet、Henrik Gulyás、Elena Fernández
DOI:10.1002/anie.201001198
日期:——
Enantiomerically enriched secondary organoboronates containing β‐carbonyl functional groups have been prepared using an unprecedented organocatalytic system (see scheme). The use of chiral tertiary phosphorus compounds induced ee values of up to 95 % in the absence of transition metals.
Catalytic compositions and methods for asymmetric aldol reactions
申请人:——
公开号:US20020147367A1
公开(公告)日:2002-10-10
Methods and compositions are provided for the direct catalytic asymmetric aldol reaction of aldehydes with donor molecules selected from ketones and nitroalkyl compounds. The reactions employ as catalyst a Group 2A or Group 2B metal complex of a ligand of formula I, as defined further herein.
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Direct Asymmetric Aldol Reactions of Acetone Using Bimetallic Zinc Catalysts
作者:Barry M. Trost、Elliad R. Silcoff、Hisanaka Ito
DOI:10.1021/ol0161211
日期:2001.8.9
[reaction: see text] The enantioselective aldolreaction using a novel binuclear zinccatalyst of acetone with several aldehydes gave products in good yields (62-89%) with a high level of enantioselectivity (ee = 76-92%).
Enantio- and diastereoselective aldol reactions of achiral ethyl and methyl ketones with aldehydes: the use of enol diisopinocampheylborinates
作者:Ian Paterson、Jonathan M. Goodman、M. Anne Lister、Russell C. Schumann、Cynthia K. McClure、Roger D. Norcross
DOI:10.1016/s0040-4020(01)85588-5
日期:1990.1
from achiral ethyl and methyl ketones by enolisation in the presence of tertiary amine bases (iPr2NEt or Et3N), undergo enantio- and diastereoselectivealdolreactions with aldehydes. The reagents employed, (+)- and (-)-(Ipc)2BOTf, are easily prepared in enantiomerically pure form in two steps from (-)- and (+)-α-pinene, respectively. The aldolreaction between ethyl ketones and aldehydes using (+)- or
Resolution of Homoallylic Alcohols Containing Dithioketene Acetal Functionalities. Synthesis of Optically Active .gamma.-Lactones by a Combination of Chemical and Enzymic Methods
作者:Yuan-Chi Pai、Jim-Min Fang、Shih-Hsiung Wu
DOI:10.1021/jo00099a036
日期:1994.10
Racemic homoallylic alcohols 1-3 containing dithioketeneacetal functionalities were prepared by addition of aldehydes to the allylic anions of ketene dithioacetals or 2-alkenyl-1,3-dithiane in a regio- and stereoselective manner. Lipase-catalyzed hydrolyses of the corresponding acetates 7-9 afforded optically active alcohols 1-3, which were treated with mercuric chloride to give gamma-lactones such as natural hop lactone, whiskey lactone, and cognac lactone.