Utilization of aldoses as a carbonyl source in cyclocarbonylation of enynes.

The reaction of enynes with acetyl-masked aldoses in the presence of a rhodium(I) catalyst resulted in cyclocarbonylation, thus avoiding the direct use of carbon monoxide, to afford bicyclic cyclopentenones. In rhodium catalysis, aldoses serve as a carbon monoxide equivalent by donating their carbonyl moieties on the acyclic aldehyde form to enynes. A variety of aldoses, including D-glucose, D-mannose, D-galactose, D-xylose, and D-ribose, can be used as a carbonyl source. Using the method, a wide variety of enynes were cyclocarbonylated in 22-67% yields. An asymmetric variant also proceeded with moderate to high enantioselectivity.