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The First Enantioselective Halo Aldol Reaction of Ethyl Propiolate and Aldehydes
Author(s) -
Chen Dianjun,
Timmons Cody,
Liu Junying,
Headley Allan,
Li Guigen
Publication year - 2004
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.200400230
Subject(s) - chemistry , enantioselective synthesis , aldol reaction , dichloromethane , lewis acids and bases , halogen , organic chemistry , selectivity , aldehyde , medicinal chemistry , catalysis , alkyl , solvent
Abstract The first enantioselective halo aldol reaction of ethyl propiolate with aldehydes has been established by using Jacobsen’s chiral cyclohexylsalen ligand. The reaction was conducted at −20 °C in dichloromethane with Et 2 AlI as the source of halogen and Lewis acid promoter. Excellent geometric selectivity (only the Z isomer) has been achieved for all 14 examples examined. The reaction works well with aromatic aldehydes; it also works with aliphatic aldehydes and α,β‐unsaturated aldehydes, albeit with diminished yields and ee . This method provides the first enantioselective synthesis of β‐iodo Morita−Baylis−Hillman (MBH) esters. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)