Green methodologies for C C and C N bond formation using transition metal catalysis and multicomponent reactions

Abstract

The carbon-carbon (C C) and carbon-nitrogen (C N) bond forming reactions represent newlineone of the most indispensable tools towards the synthesis of natural products, newlinepharmaceuticals, agrochemicals, polymers etc. This thesis is focused on the design newlineand development of benign strategies for C C and C N bond formation using various newlinetools of Green Chemistry such as multicomponent reactions (MCRs), metal supported newlineheterogeneous catalysts besides use of stable surrogates as coupling partners. newlineWherever possible, metal-free and solvent-free conditions have been explored. newlineSynthesis of various biologically important molecules such as propargylamines, newlineimidazopyridines, tetrahydroisoquinoline-indole hybrids have been achieved in an newlineenvironmentally friendly manner. newlineThe research work in the thesis is divided into four objectives: newlineObjective I: Development of A3-coupling/decarboxylative A3-coupling newlinemethodologies employing recyclable chitosan supported metal catalysts newlineTransition metal-catalyzed A3-coupling and decarboxylative A3-coupling are important newlinetransformations for the synthesis of propargylamines. This objective describes the newlineutility of chitosan supported copper based heterogeneous catalyst i.e. chitatCuI in A3- newlinecoupling and decarboxylative A3-coupling. The developed methodology offers several newlineinherent benefits such as recyclability, low catalyst loading, solventless conditions, newlinenegligible leaching of metal from the catalyst etc. Furthermore, this objective describes newlinea novel metal-free decarboxylative A3-coupling of ortho-hydroxybenzaldehydes with newlinesecondary amines and alkynoic acids. Mechanistic study revealed the involvement of newlineortho-quinonoid type of intermediate. One of the ortho-hydroxylated propargylamines, newlinevii newlinepossessing pyrrolidine ring was found to be the most potent AChE and MAO-B inhibitor newlinewith IC50 values of 0.79 ± 0.03 and#956;M and 4.27 ± 0.07 and#956;M respectively. newlineObjective II: Development of tandem protocols for C C and C N bond formation newlinefor the benign synthesis of imidazopyridine derivatives newlineImidazopyridine, is a privilege