The use of furanyl titanium compounds for the synthesis of 2,4-substituted furans

Abstract The metal derivatives 2-5, derived from the protected 4-bromo-2-furancarbaldehydes 1a,b, were reacted with the bifunctional reagent 6 bearing an aldehyde and an ester function. Whereas the Li-, Mg- and Zn-species turned out to be either unselective and/or too unreactive, the Ti-derivatives 5a,b gave the addition products 7a,b in good yield and with high chemoselectivity.