Solid-Phase Synthesis of β-Keto Esters via Sequential Baylis−Hillman and Heck Reactions

Acrylic acid was immobilized on polystyrene−Wang resin, followed by Baylis−Hillman reaction with aldehydes using DABCO as catalyst. Addition of 1 equiv of lanthanum(III) trifluoromethanesulfonate was found to improve yields, as in solution phase. After the Baylis−Hillman step, Heck reaction with aryl halides resulted in α-substituted β-keto esters, which were cleaved from the resin by acid hydrolysis with concomitant decarboxylation to afford aryl ketone products. Overall yields of 0−49% were obtained with 26 examples.