Copper(I)-catalyzed asymmetric 1,6-conjugate allylation

Abstract

Catalytic asymmetric conjugate allylation of unsaturated carbonyl compounds is usually difficult to achieve, as 1,2-addition proceeds dominantly and high asymmetric induction is a challenging task. Herein, we disclose a copper(I)-NHC complex catalyzed asymmetric 1,6-conjugate allylation of 2,2-dimethyl-6-alkenyl-4H-1,3-dioxin-4-ones. The phenolic hydroxyl group in NHC ligands is found to be pivotal to obtain the desired products. Both aryl group and alkyl group at δ-position are well tolerated with the corresponding products generated in moderate to high yields and high enantioselectivity. Moreover, both 2-substituted and 3-substituted allylboronates serve as acceptable allylation reagents. At last, the synthetic utility of the products is demonstrated in several transformations by means of the versatile terminal olefin and dioxinone groups.