Inosose phenylhydrazones

Similar spectral changes were also observed for alkaline solutions of inosose phenylhydrazones and phenylosazones. For example, 2,4,6/3,5-pentahydroxycyclohexanone phenylhydrazone (mt/o-inosose-2-phenylhy-drazone) [0.1 mM, AmaxMe2S0 282 and 304 (sh) nm] in alkaline methyl sulfoxide solution gave a band at 445 nm (with rapidly changing intensity), also associated with the diminution of the paramagnetic species this band was replaced by a new band at 382 nm. Similar behavior was observed with other inososes. 

Since the inosose phenylhydrazones could be acylated even in the presence of the strong base and isolated, it was concluded that the radical anions must arise following the abstraction of an acidic imino proton of the phenylhydrazone group by base. On interaction with oxygen the resulting anions (by an electron-transfer mechanism (29)) give... 

Figure 3. Electron spin resonance spectra of free radicals from inosose phenylhydrazones (2.5 mM to 3.5 mM, in Me2SO-l% K-tert-BuO)...

However, a base-catalyzed -elimination in the cyclohexane series, for example, of the inosose phenylhydrazone, may either stop on carbon-2 to give an arylazocyclohexene derivative (41) or, as for the inosose 1,3-bis(phenylhydrazone), proceed further leading to a complete aromatiza-tion (42). (An alternative free-radical mechanism that may explain the... 

Pentahydroxycyclohexanone Phenylhydrazone(nryo-Inos-ose-2 Phenylhydrazone) 2D-2,3,4,6/5-Pentahydroxycyclohexanone Phenylhydrazone, and 2L-2,4,5,6/3-Pentahydroxycyclohexanone Phenylhydrazone (DL-epi-Inosose Phenylhydrazone). These were prepared by the procedure of Posternak (65), mp 181° and 189°-191°C, respectively. 

A. I. Fatiadi, Bromine oxidation of inositols for preparation of inosose phenylhydrazones and phenylosazones, Carbohydr. Res., 8 (1968) 141-147. 

Elimination reactions, similar to those observed when saccharide phenylhydrazones are treated with base during acetylation, have been observed with some, but not all, inosose phenylhydrazones. Thus, treatment of... 

Attempted Acetylation of D-Mannose Phenylhydrazone. Five grams of D-mannose phenylhydrazone was acetylated as described for myo-inosose-2-phenylhydrazone. Work-up of the reaction mixture (after 24 hours) gave a yellow syrup (3.6 grams) which failed to crystallize. TLC analysis of this syrup showed only a small proportion of an olefinic... 

D-2,3,5/4,6-Pentahydroxycyclohexanone Phenylhydrazone (D-myo-Inosose-l Phenylhydrazone). This was prepared by the procedure of Magasanik and Chargaff (66), mp 196°-197°C. 

This procedure furnishes a practical method for the synthesis of inososes on a small scale. The yield is about 50%, but complete reaction is difficult to effect. The ketones can be isolated through their phenylhydrazones or by column chromatography. 

The structure of inosose mono(phenylhydrazones) is quite similar to that of acyclic saccharide hydrazones neither possess chelated rings and both exist in the Schiff-base form. Cyclization to hydrazino forms, a common process among many saccharide hydrazones, has not been observed in inosose hydrazones, probably because the resulting bicyclic compounds would be unduly strained or rigid. 

The structure of inosose bis(phenylhydrazones) resembles that of saccharide osazones in that the bishydrazone residues in both are chelated that is, bridged by an imino group (the other NH group is unchelated). 

A. J. Fatiadi, Preparation of inososes from their phenylhydrazones by use of a cation exchange resin separation of phenylhydrazones from phenylosazones, Carbohydr. Res., 1 (1966) 489-491. 

O i) Formation of Stable Free-Radicals.—The ESR probe can be used to distinguish between the hydrazine derivatives of saccharides and nonsaccharides. Saccharide phenylhydrazones, which are much less stable in basic media than inosose ph enylhydrazon es, exhibit 3-linc ESR patterns... 

---