SYNTHESIS OF SPIROCYCLIC ACETALS BY MANGANIC ACETATE PROMOTED ADDITIONS TO EXOCYCLIC ENOL ETHERS

Reaction of beta-ketoesters and beta-dicarbonyl compounds with mangani c acetate in acetic acid gives intermediates, which add to exocyclic e nol ethers to afford a variety of interesting spirocyclic acetals. As the exocyclic enol ethers are shown to be readily accessible, the resu lts constitute a useful route based on radical chemistry to the synthe sis of unsaturated spiroacetals.