Cellobiose phenylosazone anhydride

Lactose phenylosazone heptaacetate yielded lactose phenylosazone anhydride hydrate,a compound previously isolated by Fischer and by Diels and Meyer. This compound also yields a pentaacetate the same structural possibilities occur here as in the case of the cellobiose phenylosazone anhydride mentioned above. 

Although Fischer described a lactose phenylosazone anhydride in 1887, little attention was paid to substances of this type until 1935 when Diels and Meyer reported the isolation of monoanhydrides of D-glucose phenylosazone, D-galactose phenylosazone, D-xylose phenylosazone, L-arabinose phenylosazone, lactose phenylosazone, and cellobiose phenylosazone, as well as a dianhydride of maltose phenylosazone, by boiling the corresponding osazones in alcoholic solution with a little sulfuric acid. Because of the apparent identity of the D-glucose phenylosazone anhydride with the 3,6-anhydro-D-glucose phenylosazone of Fischer and Zach, Diels and Meyer formulated these compounds as 3,6-anhydrides. 

Cellobiose phenylosazone when treated by Diels method yielded a monoanhydride in the form of a hydrate. The same product was also obtained from cellobiose phenylosazone heptaacetate by deacetylation. The anhydride gave a pentaacetate proving that an oxide ring system was present, and structure XXXIII was proposed although the possibility of 1,3-anhydro- (1,5-oxide), 1,3-anhydro- (2,6-oxide) and 1,3-anhydro- (2,5-oxide) structures could not be rigidly excluded. 

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