Recent Advances in Metal-Catalyzed 1,2-Difunctionalization of Conjugated Dienes

The 1,2-difunctionalization of conjugated dienes is an important homogeneous catalytic reaction. The obtained products through 1,2-difunctionalization are widely existed in natural products and bioactive compounds, and are also sources of important organic intermediates, in addition, the preserved double bond in the difunctionalized product can be further transformed to give the desired structures or be functionalized sequentially to achieve multi-functionalization. The main difficulties focus on the encountered complex selectivities, including the regioselectivity, chemoselectivity and stereoselectivity in reactions. In recent years, with the development of organometallic chemistry, metal palladium, copper, iron or silver catalyzed 1,2-difunctionalizations of conjugated dienes have been reported in succession. In some cases the enantioselective 1,2-difunctionalizations of conjugated dienes were achieved via the introduction of chiral ligands. This review mainly focus on the recent metal catalyzed 1,2-difunctionalizations of conjugated dienes.