The adduct obtained upon consecutive treatment of 1,4-dienes with butyllithium in the presence of potassium tert-butoxide, chlorotri(isopropyloxy)titanium and a carbonyl compd. contains the a-hydroxyalkyl group invariably and exclusively linked to the 3-position of the former diene. When chlorotri(isopropyloxy)titanium is replaced by the Duthaler-Hafner reagent [(4R,5R)-chloro(cyclopentadienyl)(2,2-dimethyl-a,a,a',a'-tetraphenyl-1,3-dioxolane-4,5-dimethanolato-O,Oa)titanium] the reaction does not only occur regioselectively but also with appreciably high enantioselectivity. [on SciFinder (R)]