Xiong P,
Ivlev I,
Meggers SE.
*
Philipps-Universität Marburg, Germany
Photoelectrochemical Asymmetric Dehydrogenative [2 + 2] Cycloaddition between C–C
Single and Double Bonds via the Activation of Two C(sp
3)–H Bonds.
Nat. Catal. 2023;
DOI:
10.1038/s41929-023-01050-y
Key words
rhodium catalysis - photoelectrocatalysis - C–H bond activation
Significance
Meggers and co-workers describe an enantioselective [2 + 2] photocycloaddition between
alkyl ketones and alkenes to synthesize cyclobutanes. The method utilizes electrocatalysis
to activate two C(sp3 )–H bonds, and, under blue light irradiation, promotes coupling with two C(sp2) carbons. The procedure highlights a sustainable approach to asymmetric small ring
synthesis.
Comment
Alkyl tethered (hetero)aryl ketones and various aryl- and alkyl-substituted alkenes
can react in a highly enantioselective fashion. The transformation can be performed
on gram-scale. It is proposed that the role of ferrocene serves as a redox mediator
to turn over the electrocatalytic system, while a chiral rhodium Lewis acid mediates
the dehydrogenation of the ketone (I to VI)
and the subsequent cycloaddition (VII to IX).
