Modular Synthesis of Cyclopropane-Fused N-Heterocycles Enabled by Underexplored Diazo Reagents

Cyclopropane-fused N-heterocycles are featured in various biologically active compounds and represent attractive scaffolds in medicinal chemistry. However, synthesis routes to access structurally and functionally diverse cyclopropane-fused N-heterocycles remain underexplored. Leveraging novel α-diazo acylating agents, we report a general approach for the direct and modular synthesis of cyclopropane-fused lactams from unsaturated amines. The operationally simple transformation, which proceeds through successive acylation, (3+2) cycloaddition and fragmentation, tolerates a broad range of functional groups and yields a wide spectrum of complex molecular scaffolds, including fused, bridged and spiro ring systems. We demonstrate the utility of this transformation in the concise syntheses of therapeutic agents milnaciprane and amitifadine.

Visible-light enabled synthesis of cyclopropane-fused indolines via dearomatization of indoles

An efficient synthesis of methylene-unsubstituted cyclopropane-fused indolines via photoredox catalyzed dearomative cyclopropanation of indole derivatives was developed. A broad range of indoles bearing a variety of functional groups were compatible...

Two-Step Synthesis of α-Aryl-α-diazoamides as Modular Bioreversible Labels

α-Aryl-α-diazoamides were synthesized in two steps under mild conditions. This expeditious route employs Pd-catalyzed C-H arylation of N-succinimidyl 2-diazoacetate to obtain N-succinimidyl 2-aryl-2-diazoacetates, followed by aminolysis. The ensuing diazo compounds can esterify carboxyl groups in aqueous solution, and the ester products are substrates for an esterase. The broad scope of the synthetic route enables the continued development of diazo compounds in chemical biology.

Total syntheses of pyrroloazocine indole alkaloids: challenges and reaction discovery

Total syntheses of pyrroloazocine indole alkaloids (lapidilectines, grandilodines, lundurines and tenuisines) are discussed in terms of existing retrosynthetic solutions and novel reaction discoveries.

1,3-Iodo-amination of 2-methyl indoles via Csp2–Csp3 dual functionalization with iodine reagent

Remote iodo-amination of indole derivatives via C_sp2–C_sp3 dual functionalization under transition-metal-free conditions.

Total Synthesis of Lundurine and Related Alkaloids: Synthetic Approaches and Strategies

This review focuses on the total synthesis of lundurines A-C. Their main structural feature is a unique cyclopropa[b]indole core that has been found only in these alkaloids. In addition to this characteristic structure, the biological activity makes them as attractive synthetic targets. However, almost two decades passed from their isolation and structural determination in 1995 to their first total synthesis. The first part of this review summarizes the synthetic approaches to the tri- and tetracyclic ring systems of lundurine as well as an inter- and intramolecular cyclopropanation strategy that gives the cyclopropa[b]indole core. The second part presents a detailed description of four total syntheses that were reported from 2014 to 2016. In addition, the asymmetric total synthesis of the related alkaloids grandilodine C and lapidilectine B is described.

Generation of gold carbenes in water: efficient intermolecular trapping of the α-oxo gold carbenoids by indoles and anilines

The efficient intermolecular reaction of gold carbene intermediates, generated via gold-catalyzed alkyne oxidation, with indoles and anilines has been realized in aqueous media.