Copper-Photocatalyzed Hydroboration of Alkynes and Alkenes

The photocatalytic hydroboration of alkenes and alkynes is reported. The use of newly-designed copper photocatalysts with B(2)Pin(2) permits the formation a boryl radical, which is used for hydroboration of a large panel of alkenes and alkynes. The hydroborated products were isolated in high yields, with excellent diastereoselectivities and a high functional group tolerance under mild conditions. The hydroboration reactions were developed under continuous flow conditions to demonstrate their synthetic utility. The reaction mechanism was studied and suggested an oxidation reaction between an in situ formed borate and the Cu-photocatalyst in its excited state for the boryl radical formation.

Automated summary

A new photocatalytic hydroboration reaction using newly-designed copper photocatalysts has been reported. The reaction shows high yields, excellent diastereoselectivities, and a high tolerance for various functional groups under mild conditions. The reaction mechanism involves an oxidation reaction between an in situ formed borate and the Cu-photocatalyst in its excited state for the formation of the boryl radical.