Atropisomeric Properties of 9-Methyl-1,4-benzodiazepin-2-ones

Ryoko Tanaka, Kosho Makino, Hidetsugu Tabata, Tetsuta Oshitari, Hideaki Natsugari, Hideyo Takahashi

Research output: Contribution to journalArticlepeer-review

1 Citation (Scopus)


The atropisomeric and conformational properties of 1,4-benzodiazepin-2-ones were investigated by freezing the conformation with a methyl group at the C9 of 1,4-benzodiazepine. It was revealed that 1,4-benzodiazepin-2-ones exist only as a pair of enantiomers [(a1R, a2S) and (a1S, a2R)], which was confirmed by X-ray analysis. The absolute configuration of each atropisomer was deduced by comparing the [αE]D and CD data with those of (-)-N-methoxycarbonylmethylated 9-methyl-5-phenyl-1,4-benzodiaepin-2-one derivative. It was elucidated that the corresponding N-methylated derivative showed similar CD spectra, although the rotational direction of [E]D was opposite to that of others.

Original languageEnglish
Pages (from-to)4682-4688
Number of pages7
JournalSynthesis (Germany)
Issue number24
Publication statusPublished - 17 Dec 2021


  • 1,4-benzodiazepin-2-one
  • CD spectra
  • X-ray crystal structure analysis
  • absolute configuration
  • atropisomerism


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