Practical enantioselective synthesis of beta-substituted-beta-amino esters

J Org Chem. 2005 Jul 8;70(14):5387-97. doi: 10.1021/jo050177h.

Abstract

[reaction: see text] A practical, large-scale synthesis of a beta-amino ester 1 was developed. A chiral imine derived from (S)-phenylglycinol and 3-trimethylsilylpropanal was coupled with the Reformatsky reagent 3 with high diastereoselectivity (de > 98%) to give (SS)-4a as the major isomer. The amino alcohol residue of the coupling product 4 was oxidatively cleaved with sodium periodate in the presence of methylamine. An unusual selective oxidative cleavage of the (SS)-isomer was observed and the imine 6 was obtained with ee > 99% while the (RS)-4b isomer was not cleaved. Reaction with p-toluenesulfonic acid monohydrate allowed for the hydrolysis of the imine and the isolation of the amine as its salt. The title compound 1 was then obtained by transesterification, desilylation, and hydrochloride salt formation in a one-pot process. The method was successfully applied toward the synthesis of a wide variety of beta-amino esters.

MeSH terms

  • Aldehydes / chemistry
  • Amino Acids / chemical synthesis*
  • Amino Alcohols / chemistry
  • Benzenesulfonates / chemistry
  • Esters / chemical synthesis*
  • Ethanolamines
  • Glycine / analogs & derivatives
  • Hydrolysis
  • Imines / chemistry
  • Methylamines / chemistry
  • Models, Chemical
  • Periodic Acid / chemistry
  • Stereoisomerism
  • Trimethylsilyl Compounds / chemistry

Substances

  • Aldehydes
  • Amino Acids
  • Amino Alcohols
  • Benzenesulfonates
  • Esters
  • Ethanolamines
  • Imines
  • Methylamines
  • Trimethylsilyl Compounds
  • Periodic Acid
  • N-phenylethanolamine
  • propionaldehyde
  • metaperiodate
  • methylamine
  • 4-toluenesulfonic acid
  • Glycine