Gnanasambandam Vasuki

Four-component catalyst-free reaction in water: Combinatorial library synthesis of novel 2-amino-4-(5-hydroxy-3-methyl-1H-pyrazol-4-yl)-4H-chromene-3-carbonitrile derivatives

A catalyst-free combinatorial library of novel 2-amino-4-(5-hydroxy-3-methyl-1H-pyrazol-4-yl)-4H-chromene-3-carbonitrile derivatives has been developed by a four-component reaction between hydrazine hydrate (1), ethyl acetoacetate (2), 2-hydroxybenzaldehydes (3) and malononitrile (4) in water at ambient temperature.

Diastereoselective Multicomponent Reaction in Water: Synthesis of 2-Azapyrrolizidine Alkaloid Analogues

Synthesis of the 2-aza analogues of the pyrrolizidine alkaloid motif with two contiguous stereocenters has been achieved with high regio-, chemo-, and diastereoselectivity by an innovative multicomponent reaction in water. This elegant tactic has integrated the principles of privileged substructure-based Diversity Oriented Synthesis (pDOS) and Biology Oriented Synthesis (BIOS) to access a biologically relevant scaffold.

Synthesis and Antimicrobial Studies of Tridentate Schiff Base Ligands with Pyrazolone Moiety and Their Metal Complexes

Synthesis, characterization, and antimicrobial activity of tridentate Schiffbase ligands containing pyrazolone moiety (3a and 3b) and their transition metal complexes of VO(II), Cu(II), Fe(III), and Co(II) 4a–h have been investigated. The complexes show enhanced antibacterial activity against S. aureus, E. coli, and S. typhi and antifungal activity against C. albicans, Rhizopus sp., and A. niger compared to the ligands.

“In Water”: Organocatalyzed Diastereoselective Multicomponent Reactions toward 2-Azapyrrolizidine Alkaloid Scaffolds

Synthesis of the 2-aza analogues of pyrrolizidine and spirooxindole-2-azapyrrolizidine hybrid, a spiro-tetracyclic scaffold possessing multiple contiguous stereocenters, by an exclusive regio-, chemo-, and diastereoselective multicomponent reaction in water is reported. This logical and didactical tactic has integrated the principles of an ideal organic synthesis, privileged substructure-based diversity-oriented synthesis, and biology-oriented synthesis to access hybrid heterocyclic scaffolds.

Green chemistry oriented multi-component strategy to hybrid heterocycles

An oxindole decorated 4H-chromene scaffold has been synthesized in water under catalyst-free reaction conditions at ambient temperature in good yields with moderate to high diastereoselectivities by implementing an ingenious methodology by integrating the guiding principles of Diversity Oriented Synthesis (DOS) and green chemistry.

6-Amino-3,4-dimethyl-4-phenyl-2H,4H-pyrano[2,3-c]pyrazole-5-carbonitrile.

In the title compound, C15H14N4O, the pyrazole ring is aligned at 88.23 (4)° with respect to the aromatic ring and at 3.75 (4)° with respect to the pyran ring. In the crystal, N—H⋯N hydrogen bonds link adjacent molecules into a linear chain motif. C—H⋯N interactions are also observed.

Ethyl 2-(6-amino-5-cyano-3,4-dimethyl-2H,4H-pyrano[2,3-c]pyrazol-4-yl)acetate

In he title compound, C13H16N4O3, the pyrazole ring is planar (r.m.s. deviation = 0.054 Å). The pyran ring is not planar; the mean plane makes a dihedral angle of 1.9 (1)° with the pyrazole ring. In the crystal structure, intermolecular N—H⋯N and N—H⋯O interactions lead to a linear chain motif.

Ethyl 6-amino-5-cyano-2,4-bis­(4-methyl­phen­yl)-4H-pyran-3-carboxyl­ate

In the title compound, C23H22N2O3, the pyran ring adopts a twisted boat conformation. The tolyl rings and carboxylate group are attached to the pyran ring with torsion angles of −77.1 (2), 59.5 (3) and 17.8 (3)°, respectively. The ethyl group is disordered over two orientations with a site-occupancy ratio of 0.508 (5):0.492 (5). In the crystal, molecules are linked by N—H⋯N and N—H⋯O hydrogen bonds, generating a chain running the a axis. Weak C—H⋯O, C—H⋯N and C—H⋯π interactions are also observed.