RING ENLARGEMENT OF DICHLOROMETHYLCYCLOHEXADIENONES VIA POLYSTYRENE-SUPPORTED ORGANOTIN HYDRIDE

The ring-enlargement of dichloromethylcyclohexadienone-derivatives to tropone nuclei via organotin hydrides has been expanded and improved. It can be performed without contamination of the product with toxic ti n by-products. The employed polymer-supported organotin hydride and it s consecutive products can easily be separated from reaction mixtures by simple filtration. Examples of methyl- and benzotropones are given. The yield of the synthesis via polystyrene-supported organotin hydrid es has been compared with those of the formation via tri-n-butyltin hy dride (TBTH).