Crossed lithium dimethylhydrazone anions

Corey, Enders and Bock were among the first to describe the utility of lithium dimethylhydrazone anions for crossed aldol reactions. In the reaction shown in equation (14), an azaallyllithium reagent derived from an aldehyde dimethylhydrazone was first silylated with trimethylsilyl chloride to yield a silyl aldehyde dimethylhydrazone. Subsequent lithiation using lithium diethylamide at -20 C for 1 h generated the silylated azaallyllithium reagent (29). Subsequent addition of one equivalent of an aldehyde or ketone at -78 C and warming to -20 C then yielded the product a,p-unsaturated aldehyde dimethylhydrazone in yields of 85-95%. Hydrolysis produced the unsaturated aldehyde in 75% overall yield. 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

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