Copper(I)-Catalyzed Indolyl Ynamide Oxidation/Dearomatization: Divergent and Regioselective Synthesis of Valuable Indoline Scaffolds

A highly convenient copper(I)-catalyzed oxidation-initiated cyclopropanation of indolyl ynamide for the rapid construction of indole-fused cyclopropane-lactams is described, which represents, to the best of our knowledge, the first non-noble-metal-catalyzed indolyl ynamide oxidation/dearomatization by the in situ generated α-oxo copper carbenes. Compared to hydrazone and diazo, the use of alkynes as carbene precursors allows cyclopropanation to occur under a safe and convenient pathway. Moreover, this transformation can lead to the divergent synthesis of pentacyclic spiroindolines involving the reversal of ynamide regioselectivity by engineering substrate structures.

Cu-Catalyzed tandem cyclization and coupling of enynones with enaminones for multisubstituted furans & furano-pyrroles

A synthetic strategy that efficiently constructs complex molecular diversity in a few steps will always be embraced by organic chemists. Here, we report a cascade reaction of enynones with enaminones via carbene insertion and aryl migration to engineer distinctive multisubstituted furans with an all-carbon quaternary center, and could extend the protocol in the same pot towards furano-pyrrole bis-heterocycles. Heterogeneity of this protocol was proved with the upshot of divergent chemical space under a relatively mild reaction environment.

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...

Stereoselective Synthesis of Vinylcyclopropa[b]indolines via a Rh-Migration Strategy

A mild rhodium catalytic system has been developed to synthesize vinylcyclopropa[b]indolines through cyclopropanation of indoles with vinyl carbenoids generated from ring opening of cyclopropenes in situ. By employing a Rh-migration strategy, the products can be obtained with good to excellent E:Z ratios (≤99:1) and complete diastereoselectivity (≤99:1). This method is easy, has a low catalyst loading, and works for a broad range of functionalities.

Rhodium-Catalyzed Intermolecular Cyclopropanation of Benzofurans, Indoles, and Alkenes via Cyclopropene Ring Opening

The generation of metal carbenoids via ring opening of cyclopropenes by transition metals offers a simple entry into highly reactive intermediates. Herein, we describe a diastereoselective intermolecular rhodium-catalyzed cyclopropanation of heterocycles and alkenes using cyclopropenes as carbene precursors with a low loading of a commercially available rhodium catalyst. The reported method is scalable and could be performed with catalyst loadings as low as 0.2 mol %, with no impact to the reaction yield or selectivity.

Recent progress on donor and donor-donor carbenes

Donor and donor-donor carbenes are two important kinds of carbenes, which have experienced tremendous growth in the past two decades. This review provides a comprehensive overview of the recent development of donor and donor-donor carbene chemistry. The development of this chemistry offers efficient protocols to construct a wide variety of C-C and C-X bonds in organic synthesis. This review is organized based on the different types of carbene precursors, including diazo compounds, hydrazones, enynones, cycloheptatrienes and cyclopropenes. The typical transformations, the reaction mechanisms, as well as their subsequent applications in the synthesis of complex natural products and bioactive molecules are discussed. Due to the rapidly increasing interest in this area, we believe that this review will provide a timely and comprehensive discussion of recent progress in donor and donor-donor carbene chemistry.

Palladium-catalyzed oxidative borylation of conjugated enynones through carbene migratory insertion: synthesis of furyl-substituted alkenylboronates

A new method for the synthesis of furyl-substituted alkenylboronates has been developed by palladium-catalyzed oxidative borylation reaction of conjugated enynones.