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Issue 12, 2009
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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

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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 ∼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 dimerizationvia 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-α-L-galactopyranose to demonstrate its potential utility as a source of pseudo sugars. Experimental and spectral data are provided for all new compounds.

Graphical abstract: 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

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Publication details

The article was received on 06 Feb 2009, accepted on 09 Apr 2009 and first published on 28 Apr 2009


Article type: Paper
DOI: 10.1039/B902577B
Citation: Org. Biomol. Chem., 2009,7, 2619-2627
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    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

    F. Fabris, J. Collins, B. Sullivan, H. Leisch and T. Hudlicky, Org. Biomol. Chem., 2009, 7, 2619
    DOI: 10.1039/B902577B

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