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1.
Org Biomol Chem ; 12(29): 5484-91, 2014 Aug 07.
Article in English | MEDLINE | ID: mdl-24942816

ABSTRACT

In(OTf)3-catalyzed robust and sustainable one-pot access to previously unknown and synthetically demanding polysubstituted pyrroles via [3 + 2] annulation of α-oxoketene-N,S-acetals with ß-nitrostyrenes has been achieved under solvent-free conditions. The merit of this domino Michael addition/cyclization sequence is highlighted by its operational simplicity, short reaction time (5-10 min), good to excellent yields, tolerance of a large variety of functional groups, and efficiency of producing two new (C-C and C-N) bonds and one highly functionalized pyrrole ring in a single operation, which make it an ideal alternative to existing methods.


Subject(s)
Acetals/chemistry , Alkenes/chemistry , Chemistry, Organic/methods , Ethylenes/chemistry , Ketones/chemistry , Mesylates/chemistry , Pyrroles/chemical synthesis , Acetals/chemical synthesis , Alkenes/chemical synthesis , Catalysis , Molecular Conformation , Pyrroles/chemistry
2.
ACS Comb Sci ; 14(3): 224-30, 2012 Mar 12.
Article in English | MEDLINE | ID: mdl-22283511

ABSTRACT

A highly convergent and regioselective heteroannulation protocol for the synthesis of hitherto unreported highly substituted 2-amino-4-(aryl/alkyl)-5-(aroyl/heteroaroyl)-3-(cyano/carboalkoxy)-6-methylthio-4H-thiopyran derivatives has been developed. This one-pot three-component domino coupling of ß-oxodithioesters, aldehydes, and malononitrile/ethyl or methyl cyanoacetate is promoted by 4-dimethylamino pyridine (DMAP) in solvent (dichloromethane (DCM)) as well as under solvent-free conditions. Systematic optimization of reaction parameters identified that the three-component coupling (3CC) protocol is tolerant to a wide array of functionality providing densely functionalized 4H-thiopyrans in excellent yields. The merit of this cascade Knoevenagel condensation/Michael addition/cyclization sequence is highlighted by its high atom-economy, excellent yields, and efficiency of producing three new bonds (two C-C and one C-S) and one stereocenter in a single operation.


Subject(s)
Amines/chemistry , Esters/chemistry , Pyrans/chemical synthesis , Pyridines/chemistry , Sulfhydryl Compounds/chemical synthesis , Models, Molecular , Molecular Structure , Pyrans/chemistry , Stereoisomerism , Sulfhydryl Compounds/chemistry , X-Ray Diffraction
3.
ACS Med Chem Lett ; 3(3): 243-7, 2012 Mar 08.
Article in English | MEDLINE | ID: mdl-24936236

ABSTRACT

Leishmaniases are an epidemic in various countries, and the parasite is developing resistance against available drugs. Thus, development of new drugs against Leishmania is an open area of investigation for synthetic organic chemists. To meet this challenge, a series of chromene-2-thione derivatives have been synthesized and docked into the active site of trypanothione reductase (TryR) enzyme required for redox balance of the parasite. These were screened on promastigote, axenic amastigote, and intracellular amastigote stages of Leishmania donovani and found to show high levels of antileishmanial activity together with minimal toxicity to human peripheral blood mononuclear cells. Compounds 3b and 3k were found to be the most active among the tested compounds. Although the compounds show moderate antileishmanial activity, they identify a chemical space to design and develop drugs based on these chromene-2-thione derivatives against the Leishmania parasite.

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