Copper-catalyzed (4+3)-cycloaddition of 4-indolylcarbinols with aziridines: stereoselective synthesis of azepinoindoles.

Copper(I)-catalyzed (4+3)-cycloaddition of 4-indolylcarbinols with aziridines has been accomplished to furnish azepinoindoles. The chirality transfer, substrate scope, functional group tolerance, natural product modification and tandem C-C/C-N bond formation are the important practical features.

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 [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.

Tandem (4 + 3)-Annulation of Aziridines: Stereoselective Access to Fused Azepinoindoles.

A stereoselective tandem (4 + 3)-coupling of aziridines with 4-alkylidene indole malonates has been disclosed under Cu-catalysis involving a base-promoted annulation. The methodology serves as a potential approach toward the facile construction of fused azepinoindoles with good yields and diastereoselectivities. Late-stage natural product and drug modification as well as preliminary investigations for the enantioselective (4 + 3)-annulation 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.

Cobalt-Catalyzed Stereospecific C-N/C-O Bond Formation of Oxiranes with Diaziridines.

Co-catalyzed stereospecific C-N and C-O bond formation of oxiranes with diaziridines has been accomplished to furnish tetrahydro-[1,3,4]-oxadiazines at room temperature. Optically active oxiranes can be coupled with high optical purities (>96% ee). Stereoselectivity, functional group tolerance, mechanistic studies using DFT, and natural product modification are the important practical features.

Bi-Catalyzed 1,2-Reactivity of Spirocyclopropyl Oxindoles with Dithianediol: Access to Spiroheterocycles.

The efficient Bi-catalyzed 1,2-reactivity of spirocyclopropyl oxindoles has been disclosed with dithianediols as the sulfur surrogate to furnish spiroheterocycles at moderate temperature. The procedure provides a potential approach for the construction of spirotetrahydrothiophene scaffolds with functional group diversity. The catalytic 1,2-reactivity of cyclopropanes, mechanistic studies using density functional theory studies, diastereoselectivity, and additive-free mild conditions are the important practical features.

Transition-Metal-Free Stereospecific Oxidative Annulative Coupling of Indolines with Aziridines.

Tandem C-N bond formation for the oxidative annulation of indolines with aziridines is accomplished employing the combination of DDQ and NaOCl at ambient conditions. Optically active aziridine can be coupled with high enantiomeric purity (>99% ee). The substrate scope, stereocontrol with the enantioenriched substrate, and scale-up are the important practical advantages.