Aprotic solvents, cross-conjugated

In general, the thermodynamically stable extended dienolates (M) have been prepared by deprotonation of enones (62) with sodium or potassium alkoxides in protic solvents or with sodium or potassium hydride in aprotic solvents.Kinetically formed cross-conjugated lithium enolates may be converted into the corresponding extended systems in the presence of excess ketone but in certain cases equilibration is quite slow. Presumably, because the Tr-electron density is higher at the a-carbon than the y-carbon, extended dienolates normally react with alkylating agents to produce a-alkyl-f3,y-unsaturated ketones. 

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