Study On Palladium-catalyzed Allylation Of Chloromethylarenes With Allylsilanes

Allyl arenes are very important natural products and bioactive compounds. Compounds based on allyl arenes as backbones have been applied to many fields such as bio-chemistry, flavor & fragrance industry, food additives, and so on. Moreover, as organic synthetic intermediates, the allyl groups on allyl arenes could be further functionalized to form various functional groups, which are very useful in the development and study of natural products, functional materials, and fine chemicals.Using allylsilane as allyl reagent, a novel allylation reaction of benzyl chlorides for the synthesis of allyl arenes via ?-benzylpalladium intermediates has been developed. The reaction could be realized through the processes of allylation-dearomatization and acid catalyzed aromatization. Based on the allylation of 1-(chloromethyl)naphthalene as a model reaction, the effects of allylsilane, catalyst, solvent, additive and temperature have been systematically studied. The reaction could be occured at room temperature when it was treated with allyltrimethoxysilane (2 eq.) as allylative reagent, Pd(PPh3)4 (10 mol%) as catalyst, tetrabutylammonium fluoride (3 eq.) as additive, dichloromethane as solvent and toluene-p-sulfonic acid as Bransted acid. Under the optimized conditions, the allylation reactions proceeded smoothly to provide para-allylation products in 60%-92% yields. Mild reaction condition, high selectivity and environmental friendliness are the features of the catalytic method.