In presence of bismuth (III) chloride, a carbonylated electrophile (et
hyl mesoxalate or glyoxylate) and usual diene led selectively (65 to 1
00%) the hetero carbonyl-Diels-Alder reaction with the ene reaction pr
oduct. BiCl3 exhibits strong catalytic activity and, compared with pre
vious literature, reacts under mild conditions. (C) 1998 Elsevier Scie
nce Ltd. All rights reserved.