Electron-Deficient 3-Cyano-1-(<i>p</i>-toluenesulfonyl)-1,3-butadienes: Regio- and Stereoselective Synthesis of a Benzene Ring System by Michael-Type Addition-Cyclization with Enamines
Knoevenagel-type condensation of 4-(p-toluenesulfonyl) -2-butenenitrile (1) with aldehydes provided electron-deficient 3-cyano-1-(p-toluenesulfonyl)-1,3-(E,Z)-butadienes 2, and one of these dienes, 2a was used in a Michael-type addition-cyclization with enamines to form the benzene ring system 4.