Synthesis of pyridin-2(1H)-one derivatives via enamine cyclization

Visible-Light-Irradiated Multicomponent Reactions of Aliphatic Amines, Propiolate Acid Esters, and CF3 SO2 Na for Accessing β-CF3 Enamines

A novel one-pot two-step multicomponent reaction has been achieved for the preparation of β-CF3 enamines by using different aliphatic amines, propiolates, and CF3 SO2 Na as starting material. In this protocol, various aliphatic amines including primary amines, cyclic or acyclic secondary amines were demonstrated to be good coupling partners, and different β-CF3 enamines were obtained in moderate to good yields. Among them, the primary aliphatic amines only gave pure (E)-β-CF3 enamines as products. The synthetic utility of the MCRs strategy was further demonstrated by mild conditions, gram-scale synthesis and natural sunlight-induced protocol. Preliminary mechanistic studies suggest that this trifluoromethylation of C(sp2 )-H involves radical process.

Solvent-controlled two-step one-pot syntheses of α-X (X = Br or Cl) enamino ketones/esters and 3-(2,5-dioxopyrrolidin-1-yl)acrylate by using terminal carbonyl alkynes

A new two-step one-pot aminobromination/chlorination of carbonyl alkynes has been achieved via a Michael addition of aliphatic secondary amines and subsequent β-bromination/chlorination of the obtained enamines to afford various α-X (X = Br or Cl) enamino ketones/esters in moderate to good yields. A solvent-controllable protocol has been developed to produce versatile 3-(2,5-dioxopyrrolidin-1-yl)acrylates in moderate yields by using toluene as the solvent and chain alkyl propiolates as alkynyl substrates.

Nanocrystalline ZnO: A Competent and Reusable Catalyst for the Preparation of Pharmacology Relevant Heterocycles in the Aqueous Medium

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Nanoparticle catalyzed synthesis is a green and convenient method to achieve most of the chemical transformations in water or other green solvents. Nanoparticle ensures an easy isolation process of catalyst as well as products from the reaction mixture avoiding the hectic work up procedure. Zinc oxide is a biocompatible, environmentally benign and economically viable nanocatalyst with effectivity comparable to the other metal nanocatalyst employed in several reaction strategies. This review mainly focuses on the recent applications of zinc oxide in the synthesis of biologically important heterocyclic molecules under sustainable reaction conditions.

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Application of zinc oxide in organic synthesis: Considering the achievable advantages of this nanocatalyst, presently several research groups are paying attention in anchoring zincoxide or its modified structure in several types of organic conversions e.g. multicomponent reactions, ligand-free coupling reactions, cycloaddition reaction, etc. The advantages and limitations of this nanocatalyst are also demonstrated. The present study aims to highlight the recent multifaceted applications of ZnO towards the synthesis of diverse heterocyclic motifs. Being a promising biocompatible nanoparticle, this catalyst has an important contribution in the fields of synthetic chemistry and medicinal chemistry.

Regioselective four-component synthesis of new tetrazolo[1,5-a]quinoline-based 2-amino-1,4-dihydropyridine and pyridin-2(1H)-one derivatives using nano-ZnO catalysis

Four-component reaction between primary amines, dialkylacetylendicarboxylates, tetrazolo[1,5-a] quinoline-4-carbaldehyde and ethyl-2-cyanoacetate in the presence of 1,4-diaza-bicyclo[2.2.2]octane and zinc oxide nanoparticles results to the regioselective production of new tetrazolo[1,5-a]quinoline-based 2-amino-1,4-dihydropyridine or pyridin-2(1H)-one derivatives in good to high yields. The selectivity of the catalyzed reaction toward the generation of the dihydropyridine or pyridin-2(1H)-one derivatives was found to be strongly dependent on the size of the alkyl groups in the ester moieties of the acetylenic esters. According to single-crystal X-ray diffraction and NMR studies, the pyridin-2(1H)-one derivatives involve a restricted rotation around the C-C bond connecting the tetrazoloquinoline and dihydropyridinone cyclic systems.

Reaction Mechanism of Vinamidinium Salts and Cyanoacetamide Derivatives

The mechanism of formation of a pyridin-2(1H)-one synthesised from vinamidinium salts and cyanoacetamide derivatives is illustrated through the preparation and characterisation of a key intermediate.