Synthesis of Polysubstituted Cyclopentene and Cyclopenta[ b]carbazole Analogues from Unsymmetrical 4-Arylidene-3,6-diarylhex-2-en-5-ynal and Indole Derivatives via an Iodine Mediated Electrocyclization Reaction.

An efficient method for the synthesis of polysubstituted cyclopentene and cyclopenta[ b]carbazole derivatives through the iodine-promoted electrocyclization of substituted indoles and 4-arylidene-3,6-diarylhex-2-en-5-ynal derivatives is reported. Polysubstituted cyclopentene derivatives were produced through 4π electrocyclization reactions with indole, 7-methylindole, and 5-bromoindole as coupling partners, whereas cyclopenta[ b]carbazole derivatives were produced via 6π electrocyclization in the case of methoxy (-OMe)-substituted indoles. The methods reported herein diastereo- and regioselectively proceed under straightforward and mild conditions.

Synthesis of Benzopyridoindolone Derivatives via a One-Pot Copper Catalyzed Tandem Reaction of 2-Iodobenzamide Derivatives and 2-Iodobenzylcyanides.

An efficient approach for the synthesis of benzo-fused pyridoindolone derivatives via a one-pot copper catalyzed tandem reaction of 2-iodobenzamides with 2-iodobenzylcyanides has been developed. Using this protocol, benzo-fused pyridoindolone derivatives are obtained in high yields in a relatively short period of time under mild reaction conditions. To the best of our knowledge, this is the first approach where one can synthesize free indole N-H benzo-fused pyridoindolones. Also, both indole and pyridone cores are constructed during the course of the reaction. The methodology shows good functional group tolerance and allows synthesis of thiophene-fused pyridoindolones and fused indolobenzonaphthyridone derivatives.

Synthesis of Biologically Active Indenoisoquinoline Derivatives via a One-Pot Copper(II)-Catalyzed Tandem Reaction.

A concise route for the synthesis of indenoisoquinoline derivatives from 2-iodobenzamide and 1,3-indanedione derivatives in the presence of copper(II) chloride and cesium carbonate in acetonitrile solvent is reported. A wide variety of 2-iodobenzamide derivatives and indandiones could be used to synthesize indenoisoquinoline derivatives and other fused indenoisoquinoline in moderate to good yields. This methodology was adapted for the one-step synthesis of a series of clinically active topoisomerase I inhibitors such as NSC 314622, LMP-400, LMP-776.

Regioselective switching approach for the synthesis of α and δ carboline derivatives.

A metal-free protocol for accessing both α and δ-carboline derivatives, starting from a common indolylchalcone oxime ester precursor is reported. The reaction involves mild conditions and uses a regiodivergent approach. DDQ is used as a switching agent in selectively generating α and δ-carboline derivatives in good to moderate yields.

Palladium-Catalyzed Tandem C-H Functionalization/Cyclization Strategy for the Synthesis of 5-Hydroxybenzofuran Derivatives.

A palladium-catalyzed benzoquinone C-H functionalization/cyclization strategy with terminal alkynes was employed for the synthesis of some biologically relevant 2,3-disubstituted 5-hydroxybenzofuran derivatives. The benzoquinone acts as a reactant as well as an oxidant. During the process, an additional alkyne functionality can be introduced at the C3 position of the benzofuran. Base, ligand, and external oxidant are not required in this protocol.

Synthesis of benzo[a]carbazole derivatives from 3-ethylindoles by exploiting the dual character of benzoquinone as an oxidizing agent and dienophile.

The dual character of benzoquinone is exploited for the synthesis of benzo[a]carbazole derivatives starting from 3-ethylindole derivatives. A diene is generated in situ from the 3-ethylindole derivative with the help of benzoquinone, where it acts as an oxidizing agent. Later it serves as a dienophile and participates in a Diels-Alder reaction with the diene to afford benzo[a]carbazole derivatives.

When gold meets chiral Brønsted acid catalysts: extending the boundaries of enantioselective gold catalysis.

This review describes the development in the use of Au(I)/Brønsted acid binary catalytic systems to enable an enantioselective transformation in one-pot that cannot be achieved by gold catalysts alone. The examples discussed herein are promising since apart from using chiral ligands there exists a possibility of using chiral Brønsted acids. Clearly, the horizon for enantioselective gold catalysis has been expanded as more options to make the gold-catalyzed reactions enantioselective have become available.

Electrophile induced branching cascade: a powerful approach to access various molecular scaffolds and their exploration as novel anti-mycobacterial agents.

Herein we report on the Electrophile Induced Branching Cascade (EIBC), a new technique to produce a variety of biologically important molecular scaffolds. Some compounds exhibit excellent activities against Mycobacterium smegmatis.

Tuning the reactivity of Au-complexes in an Au(I)/chiral Brønsted acid cooperative catalytic system: an approach to optically active fused 1,2-dihydroisoquinolines.

An enantioselective cooperative catalysis protocol, utilizing achiral Au(I) complexes and chiral Brønsted acids, has been developed for the synthesis of optically pure fused 1,2-dihydroisoquinolines starting from 2-alkynylbenzaldehydes and 2-aminobenzamides.