title: Convergent synthesis, resolution, and chiroptical properties of dimethoxychromenoacridinium ions.
abstract: Cationic azaoxa[4]helicenes can be prepared in a single step from a common xanthenium precursor by addition of nucleophilic amines under monitored conditions (160 °C, 2 min, MW). The (-)-(M) and (+)-(P) enantiomers can be separated by chiral stationary-phase chromatography. Determination of the absolute configuration and racemization barrier (ΔG(⧧) (433 K) 33.3 ± 1.3 kcal·mol(-1)) was achieved by VCD and ECD spectroscopy, respectively.
authors.affiliation: Department of Organic Chemistry, ‡Department of Physical Chemistry, and §Laboratory of Crystallography, University of Geneva , Quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland.
authors.forename: Jérôme
authors.initials: J
authors.lastname: Gouin
authors.forename: Thomas
authors.initials: T
authors.lastname: Bürgi
authors.forename: Laure
authors.initials: L
authors.lastname: Guénée
authors.forename: Jérôme
authors.initials: J
authors.lastname: Lacour
mesh_terms: D000166:Acridines / Q000138:chemical synthesis* / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D001578:Benzopyrans / Q000737:chemistry*; D002942:Circular Dichroism; D008968:Molecular Conformation; D015394:Molecular Structure; D011083:Polycyclic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D014966:Xanthenes / Q000737:chemistry*
chemical_list: D000166:Acridines; D000588:Amines; D001578:Benzopyrans; D011083:Polycyclic Compounds; D000644:Quaternary Ammonium Compounds; D014966:Xanthenes; C031660:helicenes