5-azido-5-deoxy-L-sorbose

Alternatively, a mixture of 5-azido-5-deoxy-D-fructose (30) and 5-azido-5-deoxy-L-sorbose (31) (Scheme 5), obtained chemoenzymatically as it will be shown later, can be separated by chromatography, after acetonation, as 5-azido-5-deoxy-D-fructose 1,2-acetonide (33) in 22% yield and 5-azido-5-deoxy-L-sorbose 1,2-acetonide (32) in 56% yield. Treatment of 33 with Dowex (H+) resin in ethanol afforded 30, which upon hydrogenation furnished 1 in 92% yield. 

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