title: Catalyst-controlled torquoselectivity switch in the 4π ring-opening reaction of 2-amino-2-azetines giving β-substituted α,β-unsaturated amidines.
abstract: The torquoselectivity of the 4π electrocyclic ring-opening reaction of 2-azetines can be controlled by the Brønsted acidity of the catalyst and the polarity of the solvent. DFT calculations provided insight into the mechanism of this remarkable switch. Anti and syn stereoisomers of α,β-unsaturated amidines were selectively synthesized from ynamides and aldimines in the presence of Tf(2)NH and CSA, respectively.
authors.affiliation: Graduate School of Pharmaceutical Sciences, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8571, Japan.
authors.forename: Naoya
authors.initials: N
authors.lastname: Shindoh
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kitaura
authors.forename: Yoshiji
authors.initials: Y
authors.lastname: Takemoto
authors.forename: Kiyosei
authors.initials: K
authors.lastname: Takasu
mesh_terms: D000578:Amidines / Q000737:chemistry*; D000588:Amines / Q000737:chemistry*; D001385:Azetines / Q000737:chemistry*; D002219:Carbamates / Q000737:chemistry; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D000578:Amidines; D000588:Amines; D001385:Azetines; D002219:Carbamates