title: Base mediated 7-exo-dig intramolecular cyclization of Ugi-propargyl precursors: a highly efficient and regioselective synthetic approach toward diverse 1,4-benzoxazepine-5(2H)-ones.
abstract: A metal-free facile and efficient two-step synthetic protocol for the preparation of 1,4-benzoxazepine-5(2H)-one derivatives has been developed. The protocol involves Ugi reaction followed by K2CO3 mediated highly regioselective 7-exo-dig intramolecular cyclization of less-nucleophilic oxygen with the pendant alkyne moiety of an Ugi-propargyl precursor to afford the 1,4-benzoxazepine-5(2H)-one derivatives in good to excellent yields.
authors.affiliation: Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Sector 10, Jankipuram Extension, Sitapur Road, Lucknow 226031, India. Premsc58@hotmail.com prem_chauhan_2000@yahoo.com.
authors.forename: Shashi
authors.initials: S
authors.lastname: Pandey
authors.forename: S Vinod
authors.initials: SV
authors.lastname: Kumar
authors.forename: Ruchir
authors.initials: R
authors.lastname: Kant
authors.forename: Prem M S
authors.initials: PM
authors.lastname: Chauhan
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002625:Chemistry, Organic / Q000379:methods*; D003500:Cyclization; D003989:Dibenzoxazepines / Q000138:chemical synthesis* / Q000737:chemistry; D008968:Molecular Conformation; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D003989:Dibenzoxazepines