New C=C bond formation via nonstoichiometric titanium(IV) halide mediated vicinal difunctionalization of alpha,beta-unsaturated acyclic ketones

[reaction: see text] Highly stereoselective vicinal difuctionalization of alpha,beta-unsaturated ketones for the synthesis of multifunctionalized trisubstituted alkenes is described. The new reaction employs titanium(IV) halides (0.5 equiv) as promoters and inexpensive commercial chemicals as starting materials. The reaction can be performed at room temperature in a convenient vial without the protection of inert gases. Good to excellent yields and high Z/E stereoselectivity have been realized in most cases presented (16 examples).