title: 4-Dimethylamino pyridine-promoted one-pot three-component regioselective synthesis of highly functionalized 4H-thiopyrans via heteroannulation of β-oxodithioesters.
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 β-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.
authors.affiliation: Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi, India.
authors.forename: Rajiv Kumar
authors.initials: RK
authors.lastname: Verma
authors.forename: Girijesh Kumar
authors.initials: GK
authors.lastname: Verma
authors.forename: Gaurav
authors.initials: G
authors.lastname: Shukla
authors.forename: Anugula
authors.initials: A
authors.lastname: Nagaraju
authors.forename: Maya Shankar
authors.initials: MS
authors.lastname: Singh
mesh_terms: D000588:Amines / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D008958:Models, Molecular; D015394:Molecular Structure; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry*; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000588:Amines; D004952:Esters; D011714:Pyrans; D011725:Pyridines; D013438:Sulfhydryl Compounds; C522033:thiopyran