Redox-neutral zinc-catalyzed cascade [1,4]-H shift/annulation of diaziridines with donor-acceptor aziridines.

The coupling of diaziridines with donor-acceptor aziridines (DAAs) has been achieved using Zn-catalysis to furnish imidazopyrazole-4,4-dicarboxylates via [1,4]-hydride shift. The use of Zn-catalysis, [1,4]-hydride shift, natural product modification and a late-stage molecular docking study are important practical features.

Transition-Metal-Catalyzed Directed C-H Functionalization in/on Water.

Directing group assisted C-H bond functionalization using transition-metal-catalysis has emerged as a reliable synthetic tool for the construction of regioselective carbon-carbon/heteroatom bonds. Off late, "in/on water directed transition-metal-catalysis", though still underdeveloped, has appeared as one of the prominent themes in sustainable organic chemistry. This article covers the advancements, mechanistic insights and application of the sustainable directed C-H bond functionalization of (hetero)arenes in/on water in the presence of transition-metal-catalysis.

Sc(OTf)3-Catalyzed Domino C-C/C-N Bond Formation of Aziridines with Quinones via Radical Pathway.

Sc(III)-catalyzed domino C-C and C-N bond formation of N-sulfonyl aziridines with quinones has been accomplished to furnish functionalized indolines at a moderate temperature. The umpolung reactivity of aziridines, radical pathway, mild reaction conditions, substrate scope, and coupling of drug molecules in a postsynthetic application are the important practical features.

Expedient cobalt-catalyzed stereospecific cascade C-N and C-O bond formation of styrene oxides with hydrazones.

Cobalt-catalyzed cascade C-N and C-O bond formation of epoxides with hydrazones is described to furnish oxadiazines using air as an oxidant. The catalyst plays a dual role as a Lewis acid followed by a redox catalyst to accomplish the C-H/O-H cyclization. Optically active styrene oxide can be reacted enantiospecifically (>99% ee).

Expedient Ni-catalyzed C-H/C-H cross-dehydrogenative coupling of aryl amides with azoles.

A nickel-catalyzed C-H heteroarylation of arenes has been described using a removable oxazoline-aniline derived directing group. Utilization of an inexpensive nickel(II)-catalyst, substrate scope, functional group diversity and late-stage functionalization of xanthine-derived commercial drugs are the important practical features.

Pd-catalyzed bidentate auxiliary assisted remote C(sp3)-H functionalization.

Pd-catalyzed C-H functionalisation affords effective synthetic tools to construct C-C and C-X bonds. Despite the challenges, the distal functionalization of C(sp3)-H bonds has witnessed significant developments and the use of bidentate auxiliaries has garnished this area by providing an opportunity to control reactivity as well as selectivity beyond proximal sites. This article covers the recent developments on the Pd-catalyzed bidentate auxiliary-assisted distal C(sp3)-H functionalization and is categorized based on the nature of functionalizations.

Transition-Metal-Catalyzed Directing Group Assisted (Hetero)aryl C-H Functionalization: Construction of C-C/C-Heteroatom Bonds.

Transition-metal-catalyzed C-H functionalization is one of the fascinating scientific fronts in organic synthesis for the formation of conjugated arenes and has emerged as a benchmark to revolutionize the synthetic enterprise since past decades. In this realm, chelation-guided functionalization of C-H bonds using an exogenous directing group has received considerable attention recently for the expedient regioselective construction of C-C and C-heteroatom bonds as an efficient and sustainable alternative. This article outlines our contribution towards a wide variety of transformations that have been achieved by the directed C-H functionalization through the fine tuning of catalytic systems.