Axially chiral hemiaminals from nonracemic alpha-amino acid derivatives (thiohydantoins): Synthesis and isomer identification


SARIGÜL ÖZBEK S. , Dogan I.

CHIRALITY, vol.32, no.11, pp.1299-1310, 2020 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 32 Issue: 11
  • Publication Date: 2020
  • Doi Number: 10.1002/chir.23274
  • Title of Journal : CHIRALITY
  • Page Numbers: pp.1299-1310

Abstract

Stable, nonracemic axially chiral hemiaminals (O,N-hemiacetals) have been synthesized stereoselectively from lithium aluminum hydride (LiAlH4) reductions of nonracemic 5-methyl- and 5-isopropyl-3-(o-aryl)-2-thioydantoins in tetrahydrofuran (THF) at room temperature in 10 min. PredominantlyS-configured hemiaminals at C-4 of the heterocyclic ring were produced from the S-configured thiohydantoins at C-5 (by 80% when the C5 substituent is methyl and by 97% when it is isopropyl). The configuration at C-5 was retained during the reduction reaction. The stereochemical outcome of the axially chiral hemiaminals resulted from their conformational preferences.