title: Regioselective synthesis of dihydrothiophene and thiopyran frameworks via catalyst-controlled intramolecular Cγ/Cδ-S fusion of α-allyl-β'-oxodithioesters.
abstract: A highly efficient and atom-economic dual reaction manifold has been developed to synthesize 4H-thiopyran and 4,5-dihydrothiophene frameworks via regioselective intramolecular C-S fusion of α-allyl-β'-oxodithioesters. The ring size of the sulfur-heterocycles has been efficiently tuned by the use of two different catalytic systems. Palladium activates the Cδ-H of the allyl termini and facilitates the intramolecular Cδ-S coupling to furnish six-membered thiopyran skeletons exclusively. Conversely, the allylic double bond of the same substrate has been activated by BF3·Et2O to promote the Cγ-S cyclization leading to the formation of a five-membered dihydrothiophene nucleus.
authors.affiliation: Department of Chemistry, Faculty of Science, Banaras Hindu University , Varanasi-221005, India.
authors.forename: Sushobhan
authors.initials: S
authors.lastname: Chowdhury
authors.forename: Tanmoy
authors.initials: T
authors.lastname: Chanda
authors.forename: Suvajit
authors.initials: S
authors.lastname: Koley
authors.forename: Namrata
authors.initials: N
authors.lastname: Anand
authors.forename: Maya Shankar
authors.initials: MS
authors.lastname: Singh
mesh_terms: D002384:Catalysis; D015394:Molecular Structure; D011714:Pyrans / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D013463:Sulfuric Acid Esters / Q000737:chemistry*; D013876:Thiophenes / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D011714:Pyrans; D013438:Sulfhydryl Compounds; D013463:Sulfuric Acid Esters; D013876:Thiophenes; C522033:thiopyran