D-fhreo-Pentulose

Scheme 13.—First steps of synthesis of 1-deoxy-D-fhreo-pentulose from diethyl tartrate.

Acid hydrolysis of 5-amino-5-deoxy-l,2-0-isopropylidene-o -D-xy-lofuranose (15) might be expected to afiFord 5-amino-5-deoxy-D-xylose, but instead, at 70 , 3-pyridinol (21) is the main product. If the acid hydrolysis of compound 15 is conducted at room temperature, there is obtained, besides 3-pyridinol (21), the crystalline hydrochloride of l-amino-l,5-anhydro-l-deoxy-D-fhreo-pentulose hydrate (22). The crystalline hydrate exhibits no carbonyl band in its infrared and ultraviolet spectra. The water content cannot be removed without decomposition of the compound, and is, therefore, water of constitution. The nuclear magnetic resonance spectrum of 22 lacks the signal characteristic of an anomeric proton. The free ketone group is, however, detectable by the preparation of a (2,4-dinitrophenyl)-hydrazone. 

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