Premium
Evaluation of 6‐APA as a New Organocatalyst for a Direct Cross‐Aldol Reaction
Author(s) -
Emer Enrico,
Galletti Paola,
Giacomini Daria
Publication year - 2009
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.200900181
Subject(s) - chemistry , cyclohexanone , aldol reaction , stereoselectivity , enamine , yield (engineering) , imine , catalysis , organocatalysis , organic chemistry , enantioselective synthesis , materials science , metallurgy
6‐Aminopenicillanic acid (6‐APA) and two of its derivatives, 6‐APA benzyl ester (6‐APA‐OBn) and Penicillin G (PenG), have been evaluated as catalysts for use in direct cross‐aldol reactions in different solvents and mixtures. The effects of catalyst loading, reaction time, pH and temperature on the yield and stereoselectivity have been studied. 6‐APA proved to be an effective catalyst in terms of yield for the reaction between cyclohexanone and p ‐nitrobenzaldehyde, especially in neat conditions. The stereoselectivity of the reaction was conditioned by the presence of two competing mechanisms: one an imine–enamine pathway and the other a Brønsted acid catalysis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)