An efficient and base-mediated intramolecular cyclization of N-propargylamines for the synthesis of structurally diversified pyrroles in high yield has been described. The developed methodology is broadly applicable and is tolerated by a variety of functional groups. Key intermediates of natural product discoipyrrole C as well as HMG-CoA-reductase inhibitor have been successfully synthesized using developed chemistry. The proposed mechanism was supported by control experiments.

It has been shown that Pd(CH3CN)2Cl2 catalyzes the rearrangement of allylic esters. Carbamates rearrange more rapidly than acetates which in turn rearrange more rapidly than carbonates. Allylic carbamates are more rapidly isomerized by Pd(CH3CN)2Cl2 than by Hg(OCOCF3)2. The rearrangement proceeds well except in cases where the central carbon of the allylic system is fully substituted.In contrast to the reported rearrangement of allylic carbamates by Hg2+ and previous reports of Pd2+-catalyzed rearrangements of allylic esters, this work showed the latter are extremely E specific; thus, E allylic acetates yield equilibrium mixtures free of Z allylic isomers, under conditions in which Z allylic acetates are unreactive. This E specificity is applied to stereospecific 1,3-diene synthesis from bis E,Z-allylic acetates.

In the pursuit of a coherent synthetic route for the synthesis of carbo- and heterocycles, 2-alkynylarylnitrile has been recognized as a useful and versatile building block in organic synthesis due to the dual capacity of this precursor to act with a nucleophilic of electrophilic nature. The alkynes implanted at the ortho position improved the reactivity of the substrate for tandem cyclization and annulations, which led to the synthesis of diverse and complex cyclic compounds. This mini review summarizes the literature on the synthetic transformations of 2-alkynylarylnitrile into biologically relevant heterocycles as well as carbocycles such as isoindoles, isoquinolines, naphthalenes, and indenones as well as building blocks for the synthesis of various natural products. We hope that this concise review will be a promissory entry for future research in this area.

An efficient metal-free approach for the synthesis of benzimidazo-fused polyheterocycles in water.

An efficient approach for the synthesis of functionalized tetrahydro-pyrido/quinolinocarbazoles from 2-alkynylindole-3-carbaldehydes and l-proline utilizing a metal-free decarboxylative cyclization, ring expansion, and ring contraction strategy via the generation of azomethine ylide was developed. The reaction of 2-alkynylindole-3-carbaldehydes with l-thioproline leads to the formation of γ-carbolines. By virtue of this expedient method, a diverse range of biologically active heteroannulated carbazoles can be synthesized efficiently.