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Polyfunctional β‐Dicarbonyl Compounds by Michael Addition Reactions of Ester Enolates to α‐Benzylidene and α‐Alkylidene‐β‐dicarbonyl Compounds
Author(s) -
Holan Martin,
Pohl Radek,
Císařová Ivana,
Jahn Ullrich
Publication year - 2012
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.201200077
Subject(s) - chemistry , michael reaction , aldol reaction , stereoselectivity , diastereomer , meldrum's acid , dibenzoylmethane , organic chemistry , stereochemistry , medicinal chemistry , catalysis
The scope and stereoselectivity of the Michael addition of ester enolates to α‐benzylidene and α‐alkylidene β‐dicarbonyl compounds was studied. Most substrates reacted in good to excellent yields. Michael acceptors bearing carboxylic functionalities reacted directly in the β‐position, whereas aldol and Michael addition competed with unsaturated ketones. The diastereoselectivity of the process is dependent on the substitution pattern of the Michael acceptor and the geometry of the enolate. ( Z ) ‐ Enolates add to unsaturated malonates or dibenzoylmethane derivatives with good anti ‐selectivity, whereas ( E )‐enolates afforded the syn ‐diastereomers predominately. Unsaturated nitriles and Meldrum's acid derivatives reacted with low diastereoselectivity. A stereochemical model is proposed that accounts for all experimental results and allows the stereochemical outcome to be predicted.