Analysis of Interconversion between Atropisomers of Chiral Substituted 9,9’-Bicarbazole

Toshifumi Kobayashi, Fumitaka Ishiwari, Takanori Fukushima, Kengo Hanaya, Takeshi Sugai, Shuhei Higashibayashi

Research output: Contribution to journalArticlepeer-review

Abstract

Interconversion of atropisomers of chiral 3,3’-di-tert-butyl-9,9’-bicarbazole linked by a single N−N bond was analyzed by DFT calculations and experiments. The calculations revealed that the trans transition state has a lower energy for the interconversion than the cis transition state. The lowest transition state of interconversion between natural dixiamycins A and B containing a 9,9’-bicarbazole structure was found to be the trans transition state. The calculations also indicated that degradation through N−N bond cleavage was faster than racemization. Atropisomeric enantiomers of 3,3’-di-tert-butyl-9,9’-bicarbazole were resolved by chiral HPLC for the first time, and then racemization and N−N bond cleavage were investigated by heating experiments, showing that racemization did not take place below the degradation temperature.

Original languageEnglish
Pages (from-to)449-451
Number of pages3
JournalEuropean Journal of Organic Chemistry
Volume2021
Issue number3
DOIs
Publication statusPublished - 2021 Jan 22

Keywords

  • Atropisomer
  • Axis chirality
  • Bicarbazole
  • Optical resolution
  • Racemization

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Organic Chemistry

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