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Catalytic Bu4NOAc as silicon activator of ethyl 2-(trimethylsilyl) acetate, in THF, was utilized for the synthesis of β-hydroxy esters, whereas employing catalytic Bu4NOTMS gave α,β-unsaturated esters. The established reaction conditions were applicable to a diverse range of aromatic, heteroaromatic, aliphatic aldehydes and ketones. Reactions were achieved at room temperature without taking any of the specialized precautions that are in place for other organometallics. A stepwise olefination pathway via silylated β-hydroxy esters with subsequent elimination to form the α,β-unsaturated ester has been demonstrated. The key to selective product formation lies in use of the weaker acetate activator which suppresses subsequent elimination whereas stronger TMSO– activator (and base) facilitates both addition and elimination steps. The use of tetrabutyl ammonium salts for both acetate and trimethylsilyloxide activators provide enhanced silicon activation when compared to their inorganic cation counterparts. [ABSTRACT FROM AUTHOR]

An efficient synthesis of 4 H,5 H,6 H,9 H-pyrido[ ij]pyrano[3,2- c]quinolines 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h, 4i, 4j, 4k, 4l, 4m, 4n, 4o, 4p, 4q, 4r, 4s, 4t as well as spiro compound 6 was achieved via multicomponent approach by using DBU as a catalyst under the remarkably mild reaction conditions. The structures of the compounds were characterized by 1H NMR, 13C NMR, and mass spectral analysis. An attractive feature of this inexpensive protocol includes facile synthesis, shorter reaction time, ease of work-up, large number of functional group tolerance, and good to excellent yields with high purity. [ABSTRACT FROM AUTHOR]

Structurally diverse 1-aryl-10 H-[1,2,4]triazolo[3′,4′:3,4][1,2,4]triazino[5,6- b]indoles 4a- v were synthesized by regiospecific heterocyclizations. The designed molecular diversity was evaluated in vitro in parallel cell-based assays for cytotoxicity of viruses multiplication supporting cell lines and antiviral activity against viruses representative of two of three genera of the Flaviviridae family. The compound library was also tested against Retrovirus (HIV-1), two Picornaviruses (CVB-2 and Sb-1), and Paramyxoviridae (VSV) representative. Among double-stranded RNA (dsRNA) viruses, Reoviridae representative (Reo-1) was tested. Two representatives of DNA virus families were also included-HSV-1 ( Herpesviridae) and VV ( Poxviridae). The compounds 4m and 4o were found cytotoxic, having CC values ranging from 4 to 30 μM. Moreover, compound 4v has exhibited significant activity (EC = 3 μM) against BVDV. [ABSTRACT FROM AUTHOR]

Abstract: An efficient protocol for the syntheses of diverse 2,6,7- and 2,6,9-trisubstituted purines is reported starting from the guanine precursor, 2-amino-6-chloropurine nucleoside through subsequent regioselective, high yielding Mitsunobu coupling and nucleophilic substitutions at C6 with versatile primary and secondary amines. A wide range of 2,6,7- and 2,6,9-trisubstituted purines were accessible in good to excellent yields with remarkable functional group tolerance. Moreover, solvent-free, large scale synthesis of precursors 2 &3 and facile preparation of organophosphorus side chains 4 &5 were also accomplished with excellent yields. [Copyright &y& Elsevier]

Abstract: Control and prevention of tuberculosis is a major challenge, as one-third of the world’s population is infected with Mycobacterium tuberculosis. The resurgence of tuberculosis and the emergence of multidrug-resistance strains of mycobacteria, necessitate the search for new class of antimycobacterial agents. As a part of investigation of new antitubercular agents in this laboratory, we describe the syntheses of various hydrazides of comarins, quinolones and pyrroles and screening against M. tuberculosis (Mtb) H37Rv by using rifampin as a standard drug. Among the designed molecules, the most prominent compounds 2a–g, 4a and 9a showed >90% GI at MIC<6.25μg/mL. Finally, these studies suggests that compounds 2a–g, 4a and 9a may serve as promising lead scaffolds for further generation of new anti-TB agents. [Copyright &y& Elsevier]

The present investigation deals with the rapid microwave-assisted synthesis of compounds containing fused bicyclic systems. Dihydropyrimidines obtained via a microwave-assisted Biginelli reaction were treated with dibromo alkanes under microwave conditions to yield thiazolo-pyrimidine and pyrimido-thiazine systems. The usefulness of this method lies in carrying out the reaction without a catalyst and solvent in a shorter time. The reaction was successfully extended to develop fused systems from benzimidazole-2-thiol. [ABSTRACT FROM AUTHOR]

Abstract: Present study and investigations reveals that, the hydrazones of 3-acetyl-4-hydroxycoumarin undergo ring cyclization to give, 3-methyl-1-substituted phenyl-1H-chromeno[4,3-c]pyrazol-4-ones (2a–m) under the influence of microwave irradiation and by using Zn[l-proline]2, a novel Lewis acid catalyst. The overall yields of the products were found to be 82–93%. Without use of the catalyst, no reaction progress was observed. No significant changes in the overall yields of the products were observed at high microwave power and at high temperatures. The reusability of the catalyst was also checked and found up to seven cycles. [Copyright &y& Elsevier]