Bg. Van Den Hoven et al., Chemo- and regioselective cyclohydrocarbonylation of alpha-keto alkynes catalyzed by a zwitterionic rhodium complex and triphenyl phosphite, J ORG CHEM, 65(13), 2000, pp. 4131-4137
alpha-Keto alkynes react with CO and H-2 in the presence of catalytic quant
ities of the zwitterionic rhodium complex (eta(6)-C6H5BPh3)Rh--(+)(1,5-COD)
and triphenyl phosphite affording either the 2-, 2(3H)-, or 2(5H)-furanone
s in 61-93% yields. The cyclohydrocarbonylation is readily accomplished usi
ng substrates containing alkyl, aryl, vinyl, and alkoxy groups at the acety
lenic terminal, as well as a variety of primary, secondary, and tertiary al
kyl, aryl, and heteroaryl groups connected to the ketone functionality. Str
uctural and electronic properties present in the starting materials mediate
the chemo- and regioselectivity of the reaction.