Diastereoselective enzymatic preparation of acetylated pentofuranosides carrying free 5-hydroxyl groups

Methyl 3-O-acetyl-2-deoxy-α-d-ribofuranoside, 1,3-di-O-acetyl-2-deoxy-α-d-ribofuranose and 1,2,3-tri-O-acetyl-α-d-arabinofuranose were diastereoselectively prepared (de = 100%) from anomeric mixtures of the corresponding 5-acetylated compounds through Candida antarctica B lipase (CAL B)-catalysed alcoholysis.

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(1S,3S,4R)-Methyl 3-O-acetyl-2-deoxy-α-d-ribofuranosideC8H14O5[α]D20=+129.4 (c 0.06, CH3CH2OH)Source of chirality: 2-deoxy-d-ribose; enzymatic alcoholysisAbsolute configuration: (1S,3S,4R)

(1R,3S,4R)-1,3-Di-O-acetyl-2-deoxy-α-d-ribofuranoseC9H14O6[α]D20=+89.4 (c 0.04, CH3CH2OH)Source of chirality: 2-deoxy-d-ribose; enzymatic alcoholysisAbsolute configuration: (1R,3S,4R)

(1R,2S,3R,4R)-1,2,3-Tri-O-acetyl-α-d-arabinofuranoseC11H16O8[α]D20=-13.3 (c 0.12, CH3CH2OH)Source of chirality: d-arabinose; enzymatic alcoholysisAbsolute configuration: (1R,2S,3R,4R)