Jinghua Xu
Boehringer Ingelheim
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Featured researches published by Jinghua Xu.
Journal of Chromatography A | 2009
Shengli Ma; Sherry Shen; Heewon Lee; Magnus Eriksson; Xingzhong Zeng; Jinghua Xu; Keith R. Fandrick; Nathan K. Yee; Chris H. Senanayake; Nelu Grinberg
Enantiomeric separation of two aromatic alpha-substituted alanine esters was achieved on two commercially available polysaccharide-based chiral stationary phases (CSPs): amylose tris(3,5-dimethylphenylcarbamate) (ADMPC) and cellulose tris(3,5-dimethylphenylcarbamate) (CDMPC). The interactions between enantiomeric analytes and the CSPs were investigated using chromatographic methods and vibration circular dichroism (VCD). The two analytes differ on the aromatic portion of the molecules where one analyte has a pi-acceptor aromatic ring (1) while the other has a pi-donor aromatic ring (2). When an ADMPC CSP was employed, an increase in the polarity of the mobile phase leads to a reversal of the elution order for the two enantiomers of 1. The elution order of compound 2 was not affected by the polarity of the mobile phase. In order to gain an understanding of these phenomena, the enantiomeric separation of 1 and 2 was also performed on the CDMPC CSP. Interestingly, no reversal of elution order was observed upon the chromatographic separation of both pairs of enantiomers of compounds 1 and 2 upon increasing the solvent polarity when a CDMPC CSP was utilized. To understand the underlying mechanism governing these chiral separations, VCD was applied to study the structure of the ADMPC and CDMPC polymers and their conformational behaviors under chromatographic conditions. For the first time the conformations of the side chains of both polymers were revealed based on the VCD spectra along with DFT calculations. Furthermore, the interactions between the two analytes and the two CSPs were directly probed by VCD. By comparing the spectral differences of the two CSPs in the presence of the two analytes, the detailed interactions involving different functional groups associated with the chiral recognition were elucidated and thus explained the unusual reversal of elution order associated with increasing solvent polarity.
Journal of Organic Chemistry | 2006
Nathan K. Yee; Vittorio Farina; Ioannis N. Houpis; Nizar Haddad; Rogelio P. Frutos; Fabrice Gallou; Xiao-Jun Wang; Xudong Wei; Robert D. Simpson; XuWu Feng; Victor Fuchs; Yibo Xu; Jonathan Tan; Li Zhang; Jinghua Xu; Lana L. Smith-Keenan; Jana Vitous; Michael D. Ridges; and Earl M. Spinelli; Michael E. Johnson; Kai Donsbach; Thomas Nicola; Michael Brenner; Eric Winter; and Paul Kreye; Wendelin Samstag
Archive | 2006
Carl A. Busacca; Vittorio Farina; Fabrice Gallou; Nizar Haddad; Xiao-Jun Wang; Xudong Wei; Jinghua Xu; Yibo Xu; Nathan K. Yee; Li Zhang
Journal of Organometallic Chemistry | 2006
Youla S. Tsantrizos; Jean-Marie Ferland; Andrew McClory; Martin Poirier; Vittorio Farina; Nathan K. Yee; Xiao-Jun Wang; Nizar Haddad; Xudong Wei; Jinghua Xu; Li Zhang
Organic Letters | 2004
Jinhua J. Song; Nathan K. Yee; Zhulin Tan; Jinghua Xu; and Suresh R. Kapadia; Chris H. Senanayake
Journal of Organic Chemistry | 2007
Jinhua J. Song; Zhulin Tan; Jinghua Xu; Jonathan T. Reeves; Nathan K. Yee; Ranjit Ramdas; Fabrice Gallou; Katie Kuzmich; Lisa Delattre; Heewon Lee; XuWu Feng; Chris H. Senanayake
Archive | 2005
Carl A. Busacca; Vittorio Farina; Fabrice Gallou; Nizar Haddad; Xiao-Jun Wang; Xudong Wei; Jinghua Xu; Yibo Xu; Nathan K. Yee; Li Zhang
Journal of Organic Chemistry | 2005
Jinhua J. Song; Zhulin Tan; Fabrice Gallou; Jinghua Xu; Nathan K. Yee; Chris H. Senanayake
Archive | 2005
Jinhua J. Song; Zhulin Tan; Jinghua Xu; Nathan K. Yee; Chris H. Senanayake
Organic Process Research & Development | 2007
Jinhua J. Song; Jinghua Xu; Zhulin Tan; Jonathan T. Reeves; Nelu Grinberg; Heewon Lee; Katie Kuzmich; XuWu Feng; Nathan K. Yee; Chris H. Senanayake