Fructose phenylosazone

Ueber die Umwandlung des D-Fructose-phenylosazons in das Diels-Anhydro-osa-zon, by H. El Khadem, E. Schreier, G. Stohr, and E. Hardegger, Helv. Chim. Acta, 35 (1952) 993-999. 

D-arahino-Hexos-2-ulose bis(phenylhydra-zone) (o-Fructose phenylosazone)... 

Methylation was accomplished by direct conversion of the acetyl derivative as previously described. The final product contained 45% OCHs. Molecular weight determinations in benzene gave values representing 18 to 19 D-fructose residues. Hydrolytic products of the methyl derivative were separated by conversion to benzoyl derivatives. The trimethylfructose was identified as 3,4,6-trimethyl-D-fructofuranose by its phenylosazone. The authors conclude that the ratios 1 3 1 exist among the di-, tri-, and tetramethyl-D -fructoses produced by the hydrolysis. 

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. 

Pentoses and hexoaes could be distinguished readily with phenylhydra-zine. The compound hitherto called isodulcitol was identified as a sugar by means of phenylhydrazine, and was designated as rhamnose from that time on. Glucose and fructose (which H. Kiliani had discerned to be an aldohexose and a ketohexose, respectively) and mannose were found to give one and the same phenylosazone the three sugars, therefore, have the same configuration at carbon atoms 3, 4, and 5. 

Because the same phenylosazone arises from glucose, mannose, and fructose, the configurations of C3, C4, and C5 must be the same for all three sugars. 

The only dimethyl-D-fructose which has been characterized, 3,4-di-methyl-D-fructose, has been prepared by McDonald and Jackson141 from di-D-fructose anhydride I. Tritylation of this anhydride gives the 6,6 -ditrityl derivative which is methylated to 3,4,3, 4 -tetramethyl-6,6 -di-trityl-di-D-fructose anhydride I. Removal of the trityl groups followed by hydrolysis yields liquid 3,4-dimethyl-D-fructose, [ ]d —60.66° in water. It has also been obtained, with 4-methyl-D-fructose, from the hydrolysis of methylated di-D-fructose anhydride III. The structure of this dimethyl-D-fructose follows from its method of preparation from di-D-fructose anhydride I whose structure is known.10 McDonald and Jackson also prepared 3,4-dimethyl-D-fructose from inulin by the following method inulin — monotrityl inulin — monotrityl inulin diacetate — dimethyl monotrityl inulin — dimethyl isopropylidene-D-fructose — methyl dimethyl-D-fructoside —> 3,4-dimethyl-D-fructose. Its structure was confirmed by its oxidation without loss of methyl to the same lactol of the dimethyl dibasic acid obtained from 1,3,4-trimethyl-D-fructose (see page 78). The phenylosazone made from 3,4-dimethyl-D-fructose has m. p. 126° that from 3,4-dimethyl-D-glucose has not been recorded. 

The preparation of liquid 4-methyl-D-fructose, [a]D —87.5°, from di-D-fructose anhydride III has already been mentioned (see page 80). The phenylosazone, m. p. 156°, is identical with that obtained from 4-methyl-D-glucose.14a... 

McDonald and Jackson was the phenylosazone, m. p. 183-184°, which agrees well with m.p. 184-187° for the phenylosazone made from 6-methyl-D-glucose.148 An alternative synthesis of 6-methyl-D-fructose is described by Hartley and Linnell.144 They converted 6-methyl-D-glucose to 6-methyl-D-fructose through the phenylosazone and osone. Their compound was a dark brown sirup, [< ]d +17.15° in water, which gave a phenylosazone, m. p. 184°, identical (mixed m. p.) with that obtained from 6-methyl-D-glucose. 

D-fructose were removed by alcoholic fermentation and the remaining sugars, L-gulose and L-sorbose, were converted into the phenylosazone that is common to these two hexoses. Although the presence of both L-sorbose and L-gulose is altogether probable, the isolation of the so-called sorbose phenylosazone is evidence only that at least one of these unfer-mentable hexoses, or indeed sorbose (gulose) osone, was present. 

The powdered-cellulose, flowing chromatogram of an unfermentable residue from the mixture obtained by the action of heat on n-fructose yielded a sirup containing a ketose having a mobility greater than that of D-fructose it may be n-psicose. D-Psicose (identified as the phenylosazone... 

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