Chemo-enzymatic Synthesis of 3′-azido/-amino-C-4′-spirooxetano-xylo nucleosides

Author(s): Manish Kumar, Rajesh Kumar, Neha Rana, Ashok K. Prasad*.

Journal Name: Current Green Chemistry

Volume 7 , Issue 1 , 2020

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Abstract:

Conformationally locked 3'-azido-C-4'-spirooxetano-xylonucleosides T, U, C and A have been synthesized by following chemo-enzymatic convergent route. One of the 3'-azido-C-4'- spirooxetano-xylonucleosides, i.e. T was converted into 3'-amino-C-4'-spirooxetano-xylothymidine by reduction of azide to amine with H2/Pd-C in ethyl acetate in quantitative yield. The crucial step in the synthesis of spirooxetano-xylonucleosides is the Lipozyme® TL IM-mediated exclusive diastereoselective acetylation of 4-C-hydroxymethyl group in dihydroxysugar derivative, 3-azido-3-deoxy-4-Chydroxymethyl- 1,2-O-isopropylidene-α-D-xylofuranose in quantitative yield. The diastereoselective monoacetylation of 4-C-hydroxymethyl in dihydroxysugar derivative was unambiguously confirmed by X-ray crystal study on the tosylated compound obtained by the tosylation of Lipozyme® TL IM - mediated monoacetylated sugar derivative. The broader substrate specificity and exclusive selective nature of Lipozyme® TL IM can be utilised for the development of environmentally friendly methodologies for the synthesis of different sugar-modified nucleosides of importance.

Keywords: C-4`-Spirooxetano-xylonucleosides, chemo-enzymatic synthesis, lipozyme® TL IM, diastereoselectivity.

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Article Details

VOLUME: 7
ISSUE: 1
Year: 2020
Page: [119 - 126]
Pages: 8
DOI: 10.2174/2213346107666200110092413