Morita−Baylis−Hillman Reaction and Cyclization of 1-(<i>p</i>-Toluenesulfonyl)-1,3-butadiene with Aldimines

Abstract

[reaction: see text] Aldimines 2 underwent Morita-Baylis-Hillman reaction with 1-(p-toluenesulfonyl)-1,3-butadiene (3) in the presence of 3-hydroxyquinuclidine (HQD) to afford adducts 4. The E-isomers of the products cyclized to the corresponding functionalized piperidines 8 under base-catalyzed conditions. Simultaneous equilibration of (E)-4 and (Z)-4 was effected by photoisomerization to improve the efficiency of the cyclization.