title: One-pot five-component synthesis of spirocyclopenta[b]chromene derivatives and their acid-catalyzed rearrangement.
abstract: The reaction of the zwitterionic intermediate, generated in situ from either tert-butylisocyanide or cyclohexylisocyanide and acetylenedicarboxylates, with 3-cyanochromones is described, whereupon spirochromenofuran derivatives 5 or 6 were obtained in good yields. The subsequent acid-catalyzed rearrangement of the isolated 2-imino-spirochromenofurans 5 to 2-amino-spirochromenofurans 7 has also been studied. Rational mechanistic schemes for the formation of compounds 5, 6, and 7 are proposed. The structure elucidation of the products was accomplished by 1D and 2D NMR experiments and confirmed by X-ray crystallographic analysis. Full assignment of all (1)H and (13)C NMR chemical shifts has been unambiguously achieved with the aid of DFT/GIAO calculations.
authors.affiliation: Department of Chemistry, Laboratory of Organic Chemistry, Aristotle University of Thessaloniki, Thessaloniki 54124, Macedonia, Greece.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Terzidis
authors.forename: Tryfon
authors.initials: T
authors.lastname: Zarganes-Tzitzikas
authors.forename: Constantinos
authors.initials: C
authors.lastname: Tsimenidis
authors.forename: Julia
authors.initials: J
authors.lastname: Stephanidou-Stephanatou
authors.forename: Constantinos A
authors.initials: CA
authors.lastname: Tsoleridis
authors.forename: George E
authors.initials: GE
authors.lastname: Kostakis
mesh_terms: D000143:Acids / Q000737:chemistry*; D001578:Benzopyrans / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D011789:Quantum Theory; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D000143:Acids; D001578:Benzopyrans; D013141:Spiro Compounds