Jeganmohan Masilamani

Olefins are widely available feedstocks and can be readily functionalized into complex organic molecules. In particular, the regioselective allylic C–H functionalization of olefins can provide highly valuable allylic functionalized organic molecules in a highly atom- and step-economical manner. This present review describes the recent advancement on allylic C(sp3)–H functionalization of olefins catalyzed by Rh(III) or Ir(III) complexes. This review covers the advancement in the allylic C–H amination, arylation and etherification of olefins catalyzed by Rh(III) or Ir(III) complexes.

The reaction of N-aryl acrylamides with maleimides in the presence of a ruthenium/rhodium catalyst and Cu(OAc)2·H2O provided succinimide-substituted oxindole derivatives in good to excellent yields. In the reaction, 3,3′-disubstituted oxindoles are produced via a C-H alkylation and intramolecular oxidative cyclization sequence. The proposed mechanism was supported by competition experiments, deuterium labeling studies, and radical scavenger experiments.

The oxidative cyclization of substituted benzamides with maleimides assisted by 8-aminoquinoline in the presence of a catalytic amount of Co(OAc)2·4H2O provides isoindolone spirosuccinimides in good to excellent yields. The cyclization reaction was compatible with various substituted benzamides and maleimides. A possible reaction mechanism involving the C-H bond activation as a key step was proposed. The competition experiment and deuterium labeling studies were performed to investigate the mechanism of the reaction.

Maleimide and succinimide core moieties are present in various natural products and pharmaceuticals. In addition, these derivatives can be readily modified into biologically important organic molecules including pyrrolidines and γ-lactams. A transition-metal-catalyzed chelation-assisted functionalization of inert C−H bond of organic molecules with electrophiles or nucleophiles is one of the efficient methods to construct chemical bonds in a highly atom- and step-economical manner. The present review describes the recent advances in the reaction involving maleimides with organic molecules by a chelation-assisted inert C−H bond activation methodology. The reaction involving maleimides with organic molecules having directing groups, such as ketone, acyl, pyridyl, pyrimidyl, oxime, amide, imidate, chromone, azo, N-sulfonyl ketimine, carboxylic acids, and aldimines, were described. The scope, limitation and mechanistic investigation of the alkylation, annulation and alkenylation reactions were discussed elaborately. This review article includes the entire report on the chemical bond-forming reaction of maleimides with organic molecules by the C−H bond activation strategy until the end of 2018.

The reaction of benzamides with alkynes assisted by an 8-aminoquinoline ligand in the presence of Co(OAc)2·4H2O and pivalic acid under an air atmosphere provided isoquinolone derivatives in good to excellent yields. In this reaction, the active Co(iii) species is regenerated by the reaction of Co(i) species with pivalic acid under an air atmosphere with hydrogen evolution. The proposed mechanism was supported by competition experiments, deuterium labelling studies, radical scavenger experiments and kinetic studies.

A cobalt(III)-catalyzed coupling of substituted acrylamides with maleimides in the presence of 30 mol% pivalic acid providing olefin-migrated succinimide derivatives in a redox-neutral manner is described. The coupling reaction was examined with various substituted acrylamides and maleimides. The scope of the C-H alkylation reaction was also examined with substituted acrylates. A possible reaction mechanism involving a five-membered cobaltocycle as a key intermediate is proposed.