Investigation of steric and functionality limits in the enzymatic dihydroxylation of benzoate esters. Versatile intermediates for the synthesis of pseudo-sugars, amino cyclitols, and bicyclic ring systems

Org Biomol Chem. 2009 Jun 21;7(12):2619-27. doi: 10.1039/b902577b. Epub 2009 Apr 28.

Abstract

A series of benzoate esters (methyl, ethyl, n-Pr, i-Pr, n-Bu, t-Bu, allyl, and propargyl) were subjected to enzymatic dihydroxylation by E. coli JM 109(pDTG 601) strain in a whole-cell fermentation. The cis-cyclohexadienediols were obtained in yields of approximately 1g/L except for n-propyl- and i-propyl benzoate which were found to be poor substrates. n-Butyl and t-butyl benzoates were not oxidized at all. The absolute stereochemistry for all metabolites was determined by comparison with a standard prepared from (1S-cis)-3-bromo-3,5-cyclohexadiene-1,2-diol, whose absolute configuration is well established. The free diols were found to be quite stable compared to other cis-dihydrodiols of this type, however, their acetonides underwent a dimerization via a regio- and stereoselective Diels-Alder cycloaddition. The diol derived from ethyl benzoate was subjected to a stereo- and regioselective inverse electron demand Diels-Alder cycloadditions with several dienophiles. The new adducts were completely characterized. The hetero-Diels-Alder reaction of this diol with an acyl nitroso dienophile yielded regio- and stereoselectively a bicyclic oxazine, which upon reduction provided a useful derivative of amino shikimate that can be exploited in an approach to oseltamivir (Tamiflu) and other amino cyclitols. The diol was also converted to carba-alpha-L-galactopyranose to demonstrate its potential utility as a source of pseudo sugars. Experimental and spectral data are provided for all new compounds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Benzoates / chemistry*
  • Bridged Bicyclo Compounds / chemical synthesis*
  • Carbohydrates / chemistry*
  • Cyclitols / chemical synthesis*
  • Dioxygenases / metabolism*
  • Escherichia coli / metabolism
  • Esters / chemistry*
  • Esters / metabolism*
  • Galactose / chemical synthesis
  • Hydroxylation
  • Oseltamivir / chemical synthesis
  • Oxidation-Reduction
  • Pseudomonas putida / enzymology
  • Stereoisomerism

Substances

  • Benzoates
  • Bridged Bicyclo Compounds
  • Carbohydrates
  • Cyclitols
  • Esters
  • Oseltamivir
  • Dioxygenases
  • Galactose