 Titanium tetrachloride (22 mL, 0.2 mol) was added slowly by syringe to a stirred solution of benzalacetone (29.2 g, 0.2 mol) in 300 mL of dichloromethane kept at –40° (dry ice–methanol).After 5 minutes allyltrimethylsilane (30.2 g, 0.26 mol) in dichloromethane was added dropwise with stirring over 30 minutes, and the mixture stirred at –40° for a further 30 minutes.Water (400 mL) and 500 mL of ether were added and the combined organic layers were washed with saturated sodium bicarbonate solution and brine, dried (Na2SO4), and evaporated.