Iron-catalyzed cascade C-C/C-O bond formation of 2,4-dienals with donor-acceptor cyclopropanes: access to functionalized hexahydrocyclopentapyrans.

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.

Palladium-Catalyzed Weak-Chelation-Assisted C4-Nitration of Indoles with -Butyl Nitrite: Formal Access to Aminated Indoles.

Palladium-catalyzed weak-chelation-assisted C4-selective nitration of indoles has been accomplished employing -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.

Copper-Catalyzed C7-Selective C-H/N-H Cross-Dehydrogenative Coupling of Indolines with Sulfoximines.

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 -aryl 7-azaindoles with monoselectivity. The use of first-row copper catalysis, substrate scope, and late-stage synthetic applications are the important practical features.

Oxidative C-H/N-H Annulation of Aromatic Amides with Dialkyl Malonates: Access to Isoindolinones and Dihydrobenzoindoles.

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(sp)-H/C(sp)-H coupling followed by an intramolecular N-H/C(sp)-H dehydrogenative coupling to deliver the target motifs with broad scope and functional group tolerance.

Cp*Co(III)-Catalyzed C-7 C-C Coupling of Indolines with Aziridines: Merging C-H Activation and Ring Opening.

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.

Weak Coordination Enabled Switchable C4-Alkenylation and Alkylation of Indoles with Allyl Alcohols.

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.

Site-Selective Rh-Catalyzed C-7 and C-6 Dual C-H Functionalization of Indolines: Synthesis of Functionalized Pyrrolocarbazoles.

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.

Cp*Co(III)-Catalyzed Regioselective C2 Amidation of Indoles Using Acyl Azides.

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.

Exploiting Strained Rings in Chelation Guided C-H Functionalization: Integration of C-H Activation with Ring Cleavage.

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.

Ru(ii)-Catalyzed C7-acyloxylation of indolines with carboxylic acids.

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.

Expedient cobalt(ii)-catalyzed site-selective C7-arylation of indolines with arylboronic acids.

Cobalt(ii)-catalyzed pyrimidyl directing group-assisted C7 arylation of indolines with arylboronic acids has been developed using Mn(OAc)·4HO as an oxidant. The use of cobalt(ii)-PCy as a catalyst and broad substrate scope are the important practical features.