Rhodium(III)‐Catalyzed C–H Alkylation/Nucleophilic Addition Domino Reaction

Abstract

A C–H alkylation/nucleophilic addition manifold with synthetically useful aryl oximes and pyrazoles was realized by rhodium(III) catalysis under remarkably mild reaction conditions. Valuable β‐acyl substituted arylbutanoates were obtained in moderate to good yields. This strategy is characterized by excellent atom‐ and step‐economy, high chemo‐ and site‐selectivity, a broad substrate scope, and a wide functional group tolerance.

Beyond Friedel and Crafts: Directed Alkylation of C−H Bonds in Arenes

“…Mechanistic studies provided strong support for a reversible C−H bond activation and suggested the proto‐demetalation to be the rate‐limiting step, while the metalation proceeds by a carboxylate‐assisted electrophilic‐type activation. As a note, the Ackermann group later on reported an efficient rhodium(III)‐catalyzed oxime‐directed alkylation/nucleophilic addition domino process in the presence of additional ethyl glyoxylate …”

C–H bond activation and sequential addition to two different coupling partners: a versatile approach to molecular complexity

“…In 2019, Ackermann and Li expanded upon this reaction, reporting a similar addition of C–H bonds into different enones and the activated aldehyde, ethyl glyoxylate (Scheme 2(c)). 18 This work also employed Rh( iii )-catalysis to perform the same addition, with the benefit of lower catalyst loading as well as neutral conditions relative to the AcOH solvent reported by Ellman. The authors demonstrated an expanded scope of products, with 27 examples employing synthetically useful ketoxime directing groups.…”

Annulative π‐Extension (APEX): Rapid Access to Fused Arenes, Heteroarenes, and Nanographenes

“…Tang and Li developed APEX reactions of indoles with alkynylbenzaldehydes 115 to obtain 5 H ‐benzo[ b ]carbazol‐6‐yl ketones 116 in one pot (Scheme ) . Formation of the isobenzopyrylium cation intermediate 117 , derived from the alkynylbenzaldehyde triggered by coordination of the palladium catalyst, is crucial in this APEX reaction.…”