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Assignment of the absolute configuration of zwitterionic and neutral macropodumines by means of TDDFT CD calculations
Author(s) -
Guo YueWei,
Kurtán Tibor,
Krohn Karsten,
Pescitelli Gennaro,
Zhang Wen
Publication year - 2009
Publication title -
chirality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.43
H-Index - 77
eISSN - 1520-636X
pISSN - 0899-0042
DOI - 10.1002/chir.20626
Subject(s) - chemistry , time dependent density functional theory , absolute configuration , chirality (physics) , zwitterion , carbanion , computational chemistry , iminium , stereochemistry , density functional theory , crystallography , molecule , ion , organic chemistry , physics , chiral symmetry breaking , quantum mechanics , nambu–jona lasinio model , quark
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. Chirality, 2008. © 2009 Wiley‐Liss, Inc.