Rh-Catalyzed Asymmetric Allylic Substitution with Photo-Generated Alkyl Radical Species

Herein, we report a dual photoredox/Rh-catalyzed asymmetric
allylic
substitution reaction with in situ-generated alkyl radical species.
Under mild reaction conditions, a broad range of products are obtained
in 48–80% yields with 80–98% ee. Notably, the photocatalyst
plays a key role in this method, not only assisting the generation
of alkyl radicals from 4-alkyl-1,4-dihydropryidines but also facilitating
the reduction of π-allyl-Rh(III) complexes to π-allyl-Rh(II)
complexes. This strategy provides a method for Rh-catalyzed asymmetric
allylic substitution with an alkyl radical species, further expanding
the reaction patterns beyond the well-established thermal Rh-catalyzed
allylic substitution reactions.