Parallel kinetic resolution of tert-butyl (RS)-3-oxy-substituted cyclopent-1-ene-carboxylates for the asymmetric synthesis of 3-oxy-substituted cispentacin and transpentacin derivatives

Org Biomol Chem. 2008 Jun 21;6(12):2195-203. doi: 10.1039/b802428f. Epub 2008 Apr 21.

Abstract

tert-Butyl (RS)-3-methoxy- and (RS)-3-tert-butyldiphenylsilyloxy-cyclopent-1-ene-carboxylates display excellent levels of enantiorecognition in mutual kinetic resolutions with both lithium (RS)-N-benzyl-N-(alpha-methylbenzyl)amide and lithium (RS)-N-3,4-dimethoxybenzyl-N-(alpha-methylbenzyl)amide. A 50 : 50 pseudoenantiomeric mixture of lithium (S)-N-benzyl-N-(alpha-methylbenzyl)amide and lithium (R)-N-3,4-dimethoxybenzyl-N-(alpha-methylbenzyl)amide allows for the efficient parallel kinetic resolution of the tert-butyl (RS)-3-oxy-substituted cyclopent-1-ene-carboxylates, affording differentially protected 3-oxy-substituted cispentacin derivatives in high yield and >98% de. Subsequent N-deprotection and hydrolysis provides access to 3-oxy-substituted cispentacin derivatives in good yield, and in >98% de and >98% ee, while stereoselective epimerisation and subsequent deprotection affords the corresponding transpentacin analogues in good yield, and in >98% de and >98% ee.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carboxylic Acids / chemistry*
  • Cycloleucine / analogs & derivatives
  • Cycloleucine / chemical synthesis
  • Cycloleucine / chemistry
  • Kinetics
  • Models, Molecular

Substances

  • Carboxylic Acids
  • Cycloleucine
  • cispentacin