title: Assignment of the absolute configuration of zwitterionic and neutral macropodumines by means of TDDFT CD calculations.
abstract: Macropodumines B and C (1, 2) are fused pentacyclic alkaloids previously isolated from the Chinese medicinal plant Daphniphyllum macropodum. Macropodumine B (1) possesses an amazing structural feature of a cyclopentadienyl carbanion, stabilized as a zwitterion by an internal iminium cation, which was confirmed by X-ray diffraction analysis. On the basis of the X-ray geometry, the absolute configuration of 1 was determined by employing the solid-state CD/TDDFT approach. The absolute configuration of 2 was instead determined by using TDDFT CD calculations on DFT-optimized geometries, in comparison with CD spectra recorded in solution.
authors: State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences,Shanghai, People's Republic of China.
authors: Yue-Wei
authors: YW
authors: Guo
authors: Tibor
authors: T
authors: Kurtán
authors: Karsten
authors: K
authors: Krohn
authors: Gennaro
authors: G
authors: Pescitelli
authors: Wen
authors: W
authors: Zhang
mesh_terms: D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D008968:Molecular Conformation; D011083:Polycyclic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013997:Time Factors
chemical_list: D011083:Polycyclic Compounds; C520040:macropodumine B; C520039:macropodumine C