Titanocene-catalyzed regioselective alkylation of styrenes with grignard reagents using beta-bromoethyl ethers, thioethers, or amines.

Regioselective double alkylation of styrenes with alkyl Grignard reagents and alkyl bromides having a heteroatom functional group at the beta-position has been achieved by the use of a titanocene catalyst in THF. When ether was used instead of THF as a solvent, monoalkylation by substitution of a vinylic hydrogen atom with an alkyl group proceeded under similar conditions. These reactions involve the addition of alkyl radicals to styrenes to form benzylic radical intermediates.