The origin of an unusually large 19F chemical shift difference between the diastereomeric α-cyano-α-fluoro-p-tolylacetic acid (CFTA) esters of 3′,4′,5,7-tetra-o-methylepicatechin

Dirk J. Brand, Jacobus A. Steenkamp, Kenji Omata, Kuninobu Kabuto, Tomoya Fujiwara, Yoshio Takeuchi

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

During a study on the relationship between the 19F chemical shift difference for the diastereomeric α-cyano-α-fluoro-p- tolylacetic acid (CFTA) esters of chiral secondary alcohols and the absolute configurations of the alcohols, an unusually large 19F chemical shift difference has been observed for the CFTA esters of 3′,4′,5,7- tetra-O-methylepicatechin. This large chemical shift difference has been reproduced by ab initio calculations of molecular geometry and GIAO calculations of 19F chemical shifts on the stable conformations of the diastereomeric α-cyano-α-fluorophenylacetic acid (CFPA) esters of cis-flavan-3-ol as model systems. The origin of the large chemical shift difference has been further investigated using NBO analysis. This revealed that the interaction between π(C=C) of the aryl group in the chiral auxiliary and σ*(C-F) is a very important determinant of the 19F chemical shifts and this interaction depends on the torsion angle between the plane of aryl group and the C-F bond.

Original languageEnglish
Pages (from-to)351-356
Number of pages6
JournalChirality
Volume20
Issue number3-4
DOIs
Publication statusPublished - 2008 Mar 3

Keywords

  • Ab initio calculation
  • GIAO calculation
  • Molecular geometry
  • NBO analysis
  • cis-flavan-3-ol
  • α-cyano-α-fluorophenylacetic acid
  • π(C=C)-σ*(C-F) interaction

ASJC Scopus subject areas

  • Analytical Chemistry
  • Catalysis
  • Pharmacology
  • Drug Discovery
  • Spectroscopy
  • Organic Chemistry

Fingerprint Dive into the research topics of 'The origin of an unusually large <sup>19</sup>F chemical shift difference between the diastereomeric α-cyano-α-fluoro-p-tolylacetic acid (CFTA) esters of 3′,4′,5,7-tetra-o-methylepicatechin'. Together they form a unique fingerprint.

Cite this