Osazones methylation

Turanose Phenylosazone. A mixture of 4 g. of turanose, 2 ec. of water, and 1 co. of phenylhydrazine was warmed on the steam-bath until solution was complete. To the cooled solution was added 3.5 cc. of phenylhydrazine and 4 cc. of glacial acetic acid, and the mixture returned to the steam-bath for one hour. At the expiration of this time, 40 cc. of warm 60% alcohol was added and, upon cooling, a rapid crystallization of the osazone occurred. The osazone was recovered by filtration and washed with absolute alcohol followed by ether to yield 4.2 g. (69%) of lemon-yellow needles. The osazone is soluble in hot water and separates on cooling as jelly-like particles, but water is not a satisfactory solvent for its purification. It was recrystallized from 15 parts of 95% alcohol with good recovery, as needles which melted with decomposition at 200-205° and rotated [ ]d +24.5° - +33.0° (24 hours, constant value c, 0.82) in a mixture of 4 parts of pyridine, by volume, and 6 parts of absolute ethyl alcohol. In methyl cellosolve (ethylene glycol monomethyl ether) solution it rotated C< 3d" + 44.3°— + 48.5° (24 hours, constant value c, 0.80). 

It has recently been reported21 that a mixed osazone of 3,4-di-O-methyl-D-glucose can be converted, by treatment with p-nitrobenzaldehyde, into an osone which reacts with phenylhydrazine to give 3,4-di-O-methyl-D-glucose phenylosazone. Von Lebedev29 claimed to have obtained D-glu-cosone 6-phosphate, isolated as an amorphous lead salt, by the action of hydrochloric acid on the phenylosazone prepared from D-fructose 6-phosphate. 

As early as 1917, it was known that C2 and C3 in this trimethyl sugar each carried a methoxyl group, since (a) it failed to yield an osazone, and (b) the trimethyl-D-glucoheptonic acid derived from it by a cyanohydrin synthesis gave a lactone only with the concomitant loss of one of the methyl radicals.135 The production of a dimethyl- and not a trimethyl-... 

Table I. Free Radicals from Sugar Phenylhydrazones and Osazones in Methyl Sulfoxide-1 % Potassium ferf-butoxide at 25 zt 3°C...

Radical concentration, based on starting phenylhydrazone or osazone, was determined by comparison with the Fremy s salt standard solution (15), measured in methyl sulfoxide—1 % K-terJ-BuO. 

The solutions were examined in a Varian model V-4548 aqueous solution sample cell. All experiments in solution required a trace of oxygen. Freshly prepared solutions of phenylhydrazones or osazones (0.1 to 3.5 mM) in methyl sulfoxide were mixed with base [1 to 3% (90 mM to 270 mM) potassium terf-butoxide in methyl sulfoxide] and exposed to air for about 30 sec. Initial ESR spectra were recorded in about 30 sec after mixing. 

Watters, Hockett and Hudson1 have prepared a non-crystalline monomethylmannose which forms an osazone with the same properties as those of 6-methyl-n-glucosazone. The synthesis was achieved by methylation of methyl 2,3,4-triacetyl-a-D-mannopyranoside, followed by hydrolysis. Schmidt and Heiss,13 studying the epimerization of 6-methyl-D-gluconic acid, have claimed to have isolated the phenyl-hydrazide of 6-methyl-n-mannonic acid. 

On interruption of the reaction at the minimum point, only a low yield of the final product, 5-(methoxymethyl)-2-furaldehyde, could be isolated as the semicarbazone, but a crystalline phenylosazone (m.p. 120.5-121.5°, [< ]d —9° in chloroform) was obtained. It was not isolable at the end of the reaction. No osazone was obtainable from the hydroxy-glycal without prior, acid treatment. Analyses of the osazone indicated that it was a mono-O-methyl derivative of the parent CgHgCh. This is the same formula that was found by Bergmann and Zervas (see above ) for the parent of the phenylosazone obtained by direct treatment of 2,3,4,6-tetra-0-acetyl-(2-hydroxy-D-glucal) with phenylhydrazine. Whereas Bergmann and Zervas were unable to acetylate the compound further, Wolfrom, Wallace and Metcalf introduced an O-acetyl group into their mono-O-... 

Treatment of truns-[PdCl2(PhCN)2] with biacetyl-bis(N-methyl, N-phenyl)osazone (L) in CH2C12 yields the square-planar osazone complex [PdCl2L], which under suitable conditions loses HC1 to yield the internally metallated complex (23), the structure of which has previously been determined.76,77 Studies of the condensation... 

The tropolone carbonyl group does not give ketonic derivatives unless the aromaticity of the ring is much decreased, as in some benzo-fused tropolones (68MI2, p. 370). Pyridotropolones like 373 (65MI3), apparently having a 1,2-diketone structure (eventually 389), afford dioximes, dihydra-zones, osazones, and quinoxalines (Section IV,A,6,a). Their methyl ethers show the normal tropone reactivity. 

No synthesis of 4-methyl-D-xylose has been reported. The osazone has been obtained from 2,4-dimethyl-D-xylose.14... 

The only recorded derivative of 3-methyl-L-rhamnose is the phenyl-osazone, which was prepared from 2,3-dimethyl-L-rhamnose.69... 

The preparation by Irvine and Hynd of crystalline 3-methyl-D-fructose has already been described (see page 68). It gives the same osazone as 3-methyl-D-glucose. 

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