ULTRASOUND-PROMOTED PALLADIUM-CATALYZED CARBONYL ALLYLATION BY ALLYLIC ALCOHOLS WITH TIN(II) CHLORIDE IN NONPOLAR-SOLVENTS

Heterogeneous ultrasound-promoted palladium-catalyzed carbonyl allylat ion by gamma-substituted allylic alcohols with tin(II) chloride in non -polar solvents such as diethyl ether, diisopropyl ether and toluene w as carried out stepwise (first, the formation of allylic tin intermedi ates by ultrasonication, followed by the allylation of aldehydes by th e intermediates) to produce 1,4-disubstituted 3-buten-1-ols regioselec tively in moderate yields. The regioselectivity (alpha-selection) in t he ultrasound-promoted reaction is the inverse of that (gamma-selectio n) in the homogeneous palladium-catalyzed carbonyl allylation in polar solvents such as 1,3-dimethyl-2-imidazolidinone, DMF, DMSO and ethyle ne glycol. The more bulky the gamma-substituent, the higher is the alp ha-regioselectivity.