A highly efficient regioselective one-pot synthesis of 2,3,6-trisubstituted pyridines and 2,7,7-trisubstituted tetrahydroquinolin-5-ones using K5CoW12O40·3H2O as a heterogeneous recyclable catalyst

Design, synthesis and pharmacophoric model building of novel substituted nicotinic acid hydrazones with potential antiproliferative activity

“…Chemistry 6-Aryl-2-methylnicotinohydrazides 4a-c, which had not been reported hitherto, were prepared by the reaction of esters 3a-c (Kantevari et al, 2007) with hydrazine hydrate (Scheme 1). Their IR spectra showed, in each case, the appearance of absorption bands due do NH 2 and NH functions in the region 3297-3193 cm −1 in addition to the carbonyl absorption bands in the region 1643-1637 cm −1 .…”

Use of β,γ‐Unsaturated α‐Ketocarbonyls for a Totally Regioselective Oxidative Multicomponent Synthesis of Polyfunctionalized Pyridines

“…[11] For this purpose, metallo-pyridines generated from the corresponding halides [12] are widely involved but frequently hampered by the unstable nature of the precursors, while directed synthetic routes often lack of regioselectivity and offer only limited diversity. [13] Recently, we reported a metal-free Michael addition initiated three-component substrate directed route to polysubstituted pyridines 4 from 1,3-dicarbonyls 1 that could solve part of the selectivity substitution problem (Scheme 1). [14] This simple and totally regioselective multicomponent reaction (MCR) combines molecular complexity and diversity [15] with economic [16] and environmental aspects.…”

New and General Nitrogen Heterocycle Synthesis: Use of Heteropoly Acids as a Heterogeneous Recyclable Catalyst

“…They have emerged as integral backbones of more than 7,000 existing drugs. [6,7] The pyridine ring is also an integral part of agrochemicals, preparative organic chemistry, and coordination chemistry. In addition to these important biological applications, pyridine derivatives are ideal scaffolds for making libraries of drug-like compounds and generating libraries of inhibitors of HIV-1 protease and factor Xa.…”

“…Thus, the synthesis of these heterocycles is of current importance. [7] The catalytic function of heteropoly compounds [8] (heteropoly acids and salts) has attracted much attention, and they are used in solution as well as in the solid state. Because of their weak superacidic and redox properties, low toxicity, ease of handling, low cost, stability, water tolerance, recoverability, and reusability, heteropoly compounds are useful as versatile catalysts in reactions requiring electrophilic catalysis.…”

“…[9] The synthesis of pyrroles and indoles via palladium-catalyzed oxidation of hydroxyenaminones was reported by Ohta, [12] and this procedure was extended to the synthesis of potential central nervous system agents by Ravina. [7] In this communication, we describe the alternative efficient synthesis of six-membered (tetrahydroquinolin-5-ones, pyridine) and five-membered (pyrrole and tetrahydroindol-4-ones) nitrogen heterocyclic compounds, which were prepared by condensation of the b-dicarbonyl compounds with the corresponding b-or c-amino alcohols, and subsequent cyclization followed by spontaneous aromatization (Scheme 2).…”