In this Communication, we report an unprecedented β‐regioselective radical inverse hydroboration (compared with ionic hydroboration) of α,β‐unsaturated amides with NHC‐BH3 enabled by photoredox catalysis. Density functional theory (DFT) calculations show that the unique photoredox cycle is a key factor to control the β‐regioselective radical hydroboration, by lowering the energy barrier in comparison with other pathways. This protocol provides a general and convenient route to construct a wide range of structurally diverse β‐borylated amides in synthetically useful yields under mild conditions.

A metal- and photo-free method for the perfluoroalkylative pyridylation of alkenes has been developed.

A B(C6F5)3‐catalyzed hydroarylation of a series of 1,3‐dienes with various phenols has been established through a combination of theoretical and experimental investigations, affording structurally diverse ortho‐allyl phenols. DFT calculations show that the reaction proceeds through a borane‐promoted protonation/Friedel–Crafts pathway involving a π‐complex of a carbocation–anion contact ion pair. This protocol features simple and mild reaction conditions, broad functional‐group tolerance, and low catalyst loading. The obtained ortho‐allyl phenols could be further converted into flavan derivatives using B(C6F5)3 with good cis diastereoselectivity. Furthermore, this transformation was applied in the late‐stage modification of pharmaceutical compounds.

A practical and efficient Lewis acid-catalyzed radical–radical coupling reaction of N-hydroxyphthalimide esters and 4-cyanopyridines with inexpensive bis­(pinacolato)­diboron as reductant has been developed. With ZnCl2 as the catalyst, a wide range of quaternary 4-substituted pyridines, including highly congested diarylmethyl and triarylmethyl substituents, could be selectively obtained in moderate to good yields with broad functional group tolerance. Combined theoretical calculations and experimental studies indicate that the Lewis acid could coordinate with the cyano group of the pyridine-boryl radical to lower the activation barrier of the C–C coupling pathway, leading to the formation of 4-substituted pyridines. Moreover, it could also facilitate the decyanation/aromatization of the radical–radical coupling intermediate.

No abstract