Enolates alkali metal, conjugate addition

The Michael reaction is the conjugate addition of a soft enolate, commonly derived from a P-dicarbonyl compound 24, to an acceptor-activated alkene such as enone 41a, resulting in a 1,5-dioxo constituted product 42 (Scheme 8.14) [52]. Traditionally, these reactions are catalyzed by Bronsted bases such as tertiary amines and alkali metal alkoxides and hydroxides. However, the strongly basic conditions are often a limiting factor since they can cause undesirable side- and subsequent reactions, such as aldol cyclizations and retro-Claisen-type decompositions. To address this issue, acid- [53] and metal-catalyzed [54] Michael reactions have been developed in order to carry out the reactions under milder conditions. 

Alkali metal (Li, Na, K) enolates can undergo kinetic conjugate addition... 

It is not essential to have two anion-stabilizing groups for successful conjugate addition and it is even possible with simple alkali metal (Li, Na, and K) enolates. Lithium enolates are not ideal nucleophiles for thermodynamically controlled conjugate addition. Better results are often observed with sodium or potassium enolates, which are more dissociated and thus more likely to revert. Lithium binds strongly to... 

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