ALKYLATION OF ENOL ETHERS OBTAINED BY TREATMENT OF ALPHA,BETA-UNSATURATED ACETALS WITH ORGANOPOTASSIUM REAGENTS - AN INVERSE POLARITY APPROACH

The reaction of alpha,beta-unsaturated acetals 1-4 with sec-butyllithi um (2 equiv.) in the presence of potassium tert-butoxide in tetrahydro furan at -95-degrees-C gave, as a result of 1,4 elimination, alpha-met allated enol ethers. The latter react with alkyl halides and carbonyl compounds to afford substitution and addition products. In particular, for the reaction with the acetal 1 and D2O as the electrophile, the a lpha-deuteriated enol ether 5 cyclizes to [2-H-2]-2-(prop-1-enyl)-1,3- dioxane.