Crossed aldol reaction using cross-linked polymer-bound lithium dialkylamide

Cross-linked polymer-bound lithium dialkylamides were employed in crossed aldol reaction of various carbonyl compounds with aldehydes to afford the corresponding β-hydroxycarbonyl compounds. The introduction of spacer chains to the polymer-bound lithium dialkylamide between the base moiety and the polystyrene backbone effectively enhanced yields of the desired aldol adducts. Sometimes better yields were obtained by using the polymer-bound reagent having an appropriate spacer-chain with those obtained using lithium diisopropylamide under homogeneous conditions. Repeated use of these polymeric reagents was demonstrated with no loss of efficiency.