Rh^III‐Catalyzed Directed Selective C7‐Hydroxylation and Acetoxylation of Indolines

Abstract

Cp*RhIII‐catalyzed selective C7‐hydroxylation and acetoxylation reactions of indolines under mild conditions have been developed. The reactions are directed by a removable pyrimidyl group and have high functional group tolerance. It provides a mild access to hydroxylated and acetoxylated indolines in moderate to excellent yields.

RhRu Bimetallic Oxide Cluster Catalysts for Cross-Dehydrogenative Coupling of Arenes and Carboxylic Acids

“…A single Rh 4 O 6 cluster (without carbon support) was employed as the model catalyst because of its highly symmetrical structure with pseudo- T d symmetry (Figure S15a). Similar structures have been experimentally observed in gas-phase studies on rhodium oxide cluster cations isolated in vacuum. , Considering that acetoxylation and some other C–H activation reactions of arenes catalyzed by Rh complexes proceed by Rh­(III)/Rh­(V) redox cycling, − ,− and that our reaction system was operated under a high O 2 pressure and high temperature, we examined both Rh­(III)–acetate and Rh­(V)–acetate species (in Rh 4 O 5 (OAc) 2 and Rh 4 O 6 (OAc) 2 cluster models, respectively; Figure S15b,c) as candidates for the active center of the C–H bond activation reaction (Figure ). Calculated Gibbs free energies of the model clusters suggested that the generation of Rh­(V) species on the Rh oxide clusters by O 2 is thermodynamically possible.…”

“…Cross-dehydrogenative coupling (CDC) reactions between aromatic C–H and X–H (X = C, N, O) bonds have recently attracted considerable interest owing to their step/atom economy. − CDC reactions between arenes and carboxylic acids can produce aryl esters directly from nonactivated substrates . Homogeneous catalysts such as Co, Ru, − Rh, − Pd, − and Au , complexes have been developed for the coupling of arenes and carboxylic acids (Figure a). Oxidants are generally required for these reactions to occur.…”

Recent Advancements on Transition‐Metal‐Catalyzed, Chelation‐Induced ortho‐Hydroxylation of Arenes

“…), the C‐7 hydroxylation product was obtained (Scheme 60). [73c] Based on the literature reports and mechanistic study, a mechanism was proposed by the authors. Initially, [RhCp*Cl 2 ] 2 forms an active species [RhCp*(OAc) 2 ] in presence of PhI(OAc) 2 .…”

Rh(III)‐Catalyzed Selective C7 Halogenation of Indolines

“…In this direction, transition metal‐catalysis has witnessed tremendous growth particularly for regioselective functionalization of indoline scaffold at C7 position. Due to high selectivity and catalytic efficacy displayed by rhodium(III) catalyst, [7,8b] it is well explored for C7 functionalization of indolines such as alkylation, [8c,f,j] alkenylation, [8f] alkynylation, [8a,f] allylation, [8b,f,h] arylation, [8g] amination, [8f,i] acetoxylation, [8d,e] carbonylation, [8f] cyanation [8f] and thiolation [8f] (Scheme 2a). Besides these reports, a number of methodologies for ortho ‐C−H halogenation has been reported using N‐ halosuccinimides with different transition metal catalysts, amongst which rhodium catalyst is widely explored [9a] .…”