Copper-catalyzed 1,2-dioxygenation of 1,3-dienes with tert-butyl benzoperoxoate at room temperature†

The involvement of transition metals and radicals in the selective difunctionalization of conjugated dienes has proved to be one of the practical strategies for the rapid synthesis of promising allylic compounds. Herein, we report a protocol for copper-catalyzed 1,2-dioxygenation of 1,3-dienes with tert-butyl benzoperoxoate (TBPB) at room temperature. This strategy features mild reaction conditions, excellent atom economy, and good regio- and chemoselectivity, providing a straightforward and efficient approach for the synthesis of allyl esters. In particular, this free-radical double C–O bonding process can be carried out in the aqueous phase and the first attempts on asymmetric synthesis have been made to obtain modest to good enantioselectivity. Mechanistic studies have demonstrated that the SET process of the Cu(i) catalyst with TBPB and the generation of allyl radical intermediates are essential for the successful conduct of this difunctionalization ploy.