A Lewis acid promoted asymmetric umpolung reaction with chiral N-sulfinyl imines as the electrophiles

Xin Xu, Jun Ying Liu, Dian Jun Chen, Cody Timmons, Guigen Li

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

An new asymmetric umpolung reaction has been developed by reacting N-sulfinyl imines with 2-lithio-2-phenyl-1,3-dithiane. The reaction was conducted at between -20 and -25°C in THF in the presence of Et 2AlCl as the Lewis acid promoter. Excellent diastereoselectivities (up to >95% de) and chemical yields (64-95%) have been achieved for nine substrates with all individual isomers separated and characterized. The absolute structure of the chiral products has been unambiguously determined by synthetic conversions to a known sample. 2-Lithio-2-phenyl-1,3-dithiane was found to be much less reactive than its 2-methyl counterpart, which was reported very recently. All individual isomers have been readily separated by column chromatography. The absolute structure of the chiral products has been unambiguously determined by conversion into a known compound. This method provides an easy access to enantiomerically pure ctamino ketones.

Original languageEnglish
Pages (from-to)1805-1809
Number of pages5
JournalEuropean Journal of Organic Chemistry
Issue number9
DOIs
StatePublished - Apr 29 2005

Keywords

  • 1,3-Dithianes
  • Amino ketones
  • Asymmetric synthesis
  • N-Sulfmyl imines
  • Umpolung

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