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Direct Asymmetric Aldol Reactions in Water Catalysed by a Highly Active C 2 ‐Symmetrical Bisprolinamide Organocatalyst
Author(s) -
Delaney Joshua P.,
Henderson Luke C.
Publication year - 2012
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201100667
Subject(s) - chemistry , aldol reaction , cyclohexanone , cyclopentanone , catalysis , aldehyde , organocatalysis , organic chemistry , enantioselective synthesis
A novel C 2 ‐symmetrical bisprolinamide organocatalyst was synthesised and used to facilitate asymmetric direct aldol reactions in a water emulsion. Reactions were performed at room temperature with very low catalyst loadings (1–2.5 mol%) without the required use of additives, co‐catalysts or extended reaction times (24 h). This catalyst system was then used with a variety of aldehyde substrates showing good reaction generality for benzaldehydes with cyclohexanone ( dr range 77/23 to >99/1, anti/syn ; ee range 33% to >99%) and moderate scope with cyclopentanone ( dr range 45/55 to 76/24, anti/syn ; ee range 14% to 68%). Ultra‐low catalysts loadings (0.1 and 0.05 mol%) were also investigated demonstrating catalyst turnover numbers in the order of 1000.