Phenyl Hydrazones, Osazones, and Formazans

Treatment of brominated 3,4-di-O-acetyl-o-xylal with p-nitrophenylhydrazine gave a mixture of the 3,4-di-0-acetyl-2,5-anhydro-D-xylose and -D-xylose p-nitrophenylhydrazones both these compounds and their deacetylated derivatives exhibited a preference for the Ti conformation. Acetylation of L-rhamnose benzoylhydrazone with acetic anhydride and pyridine has been shown to give the a-pyranose derivative (14) rather than the acyclic hydrazone (15) previously claimed (see Vol. 10, p. 74). With acetic anhydride and zinc chloride, compound (14) gave 1,2,3,4-tetra-O-acetyl-a-L-rhamnose, whereas (15) gave the oxadiazoline (16).  

El Ashry s group have continued studies on the chemistry of hydrazone derivatives of L-ascorbic acid and its D-erythro epimer. 2-Mono and 2,3-bis-hydrazones of dehydro-L-ascorbic acid can be prepared, which may be cyclized 

Rockenbauer, J. Hemela, G. Toth, and A. Gerecs, Magyar K6m. Folydirat, 1977, 83, 

Reagents i, NaBH -EtOH ii, NaBHjCN-EtOH-HsO iii, NaBHsCN-IR 120 (H+) 

Arylhydrazone and bis-arylhydrazone derivatives of lactose have been prepared, and their periodate oxidation studied the formation of an osone derivative by hydrazinolysis of the bisbenzoylhydrazone is noted in Chapter 14.  

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