DESIGN AND SYNTHESIS OF NOVEL METHODOLOGIES FOR FUSED N-HETEROCYCLIC DERIVATIVES THROUGH MCR SEQUENCES

Abstract

The thesis entitled “Design and Synthesis of Novel Methodologies for Fused N-heterocyclic Derivatives through MCR Sequences” is divided into eight chapters. In this context, the present thesis deals with the development of new multicomponent methodologies for the synthesis of nitrogen-fused complex heterocycles and polyheterocycles. A series of N-fused heterocyclic scaffolds were synthesized in good to excellent yields by using regioselective Groebke–Blackburn–Bienaymé (GBB) reaction, post-GBB condensations, A3-coupling reaction, Knoevenagel condensation, Michael addition, and [4+1] formal annulation reactions. Furthermore, a number of exciting new methodologies have been developed to access diverse array of pharmaceutically-relevant cores. These methodological transformations are tolerant of a variety of functionalities, thus giving broad substrate scope.

• Chapter 1, describes an approach towards one-pot synthesis of novel N-fused tricyclic heterocyclic scaffolds via Groebke–Blackburn–Bienaymé (GBB) reaction. • Chapter 2, deals with the one-step construction of novel amino-indazolo[3’,2’:2,3]imidazo[1,5-c]quinazolin-6(5H)-one polyheterocycles via a sequential post-GBB cyclization/spiro ring expansion triggered by a [1,5]-hydride shift. • Chapter 3 describes our efforts toward the green synthesis and characterization of silver nanoparticles (Ag NPs) from extract of plant Radix Puerariae and their catalytic application for the construction of pyrimido[1,2-b]indazole derivatives under solvent-free conditions. • Chapter 4 deals with the development of catalyst-free one-pot multi-component protocol for the synthesis of novel benzo[d]imidazo[2,1-b]thiazol-3-yl)-2H-chromen-2-one in ethanol–PEG-600. • Chapter 5 deals with the iron-catalyzed one-pot synthesis of benzo[d]imidazo[2,1-b]thiazole derivatives under solvent-free conditions. • Chapter 6 describes our efforts toward development of Fe-catalyzed microwave-promoted one-pot synthesis of benzo[b][1,4]thiazine-4-carbonitriles under solvent-free condition. • Chapter 7 deal with the synthesis of bifunctionalized spiro[indazolo[3,2-b]quinazoline-7,3'-indoline hybrids by using one-pot four-component domino reaction. • Chapter 8 deals with the development of diversity-oriented one-pot synthesis of densely functionalized furan biheteroaryls via isocyanide insertion.