Cr-waste free catalytic carbonyl addition reactions with polymer-immobilized CrF2

A monomeric [Cr(pyridine)4F2]+Br− is immobilized onto the dipyridyl-TentaGel resin. Allylations of aldehydes with 5-10 mol % of the CrF2-dipyridyl-TentaGel resin 2/Mn/TMSCl in THF provide the corresponding homoallylic alcohols in excellent yields after TMS-desilylations with a polymer-supported ammonium fluoride 3. The recovered CrF2-dipyridyl-TentaGel resins can be utilized multiple times without a decrease of reactivity.