RESUMEN
Iron-catalyzed cascade C-C and C-O bond formation of 2,4-dienals with donor-acceptor cyclopropanes (DACs) has been developed to furnish hexahydrocyclopentapyrans. Optically active DACs can be coupled stereospecifically (>97% ee). Chirality transfer, use of iron-catalysis and substrate scope are the salient practical features.
RESUMEN
Palladium-catalyzed weak-chelation-assisted C4-selective nitration of indoles has been accomplished employing tert-butyl nitrite in the presence of oxone under molecular oxygen at a moderate temperature. Aerobic conditions, C4-selectivity, substrate scope, conversion to valuable aminated indoles, and late-stage natural product modifications are the important practical features.
RESUMEN
Cu-catalyzed cross-dehydrogenative coupling of the C7 C-H bond of indolines with sulfoximines has been accomplished. The reaction can be extended to the cross-dehydrogenative coupling of N-aryl 7-azaindoles with monoselectivity. The use of first-row copper catalysis, substrate scope, and late-stage synthetic applications are the important practical features.
RESUMEN
A copper-mediated oxidative C-H/N-H annulation of aromatic amides with dialkyl malonates has been presented to afford synthetically valuable dihydrobenzoindoles and isoindolinones. The reaction proceeds through direct oxidative C(sp2)-H/C(sp3)-H coupling followed by an intramolecular N-H/C(sp3)-H dehydrogenative coupling to deliver the target motifs with broad scope and functional group tolerance.
RESUMEN
A Cp*Co(III)-catalyzed directing group-assisted C7 C-C coupling of indolines with aziridines has been developed by merging C-H activation and ring opening. The use of cobalt catalyst, detection of a Co(III) intermediate, and late-stage removal of the directing group are important practical features.
RESUMEN
A weak carbonyl coordination facilitated tunable reactivity between alkenylation and alkylation of indoles at the C4 C-H site is presented using readily accessible allylic alcohols in the presence of Rh catalysis by switching the additives or directing group. Exclusive site selectivity, functional group tolerance, and late-stage modifications are the important practical features.
RESUMEN
A site-selective dual C-7 and C-6 C-H functionalization of indolines with azabenzonorbornadienes has been accomplished using Rh-catalysis. The reaction affords a potential route toward pyrrolocarbazoles with broad scope and functional group tolerance.
RESUMEN
A cobalt-catalyzed C2-selective amidation of indoles using acyl azides has been accomplished. Isotope experiments suggest that C-H activation is reversible. The use of sustainable Co catalysis, functional group diversity, substrate scope, and regioselectivity are the important practical features.
RESUMEN
Strained ring systems are regarded as privileged coupling partners in directed C-H bond functionalization and have emerged as a potential research area in organic synthesis. The inherent ring strain in these systems acts as a driving force, allowing the facile construction of diversified structural scaffolds via integrating C-H activation and ring-scission. The mechanistic underpinnings allows the implementation of a plethora of C-H bonds across plentiful organic substrates, including the less reactive alkyl ones. Considering the synthetic space, this area will foster developments of novel synthetic methods in chelation guided C-H functionalization. This review will focus on recent developments in transition-metal catalyzed chelation assisted concomitant C-H activation and ring scission of strained rings to attain molecular complexity.
RESUMEN
Ruthenium(ii)-catalyzed site-selective C7-acyloxylation of indolines with carboxylic acids is presented. The substrate scope and functional group tolerance are important practical features. The kinetic isotope studies suggest that C-H bond activation may be the rate-determining step.
RESUMEN
Cobalt(ii)-catalyzed pyrimidyl directing group-assisted C7 arylation of indolines with arylboronic acids has been developed using Mn(OAc)2·4H2O as an oxidant. The use of cobalt(ii)-PCy3 as a catalyst and broad substrate scope are the important practical features.