Compound A, known to be a monomethyl ether of D-glucose, can be oxidized to a carboxylic acid B with bromine water. When the calcium salt of B is subjected to the Ruff degradation, another aldose monomethyl ether is obtained that can also be oxidized with bromine water.

When A is subjected to the Kiliani–Fischer synthesis, two new methyl ethers are obtained. Both are optically active, and one of them can be oxidized with dilute nitric acid to an optically inactive compound. Suggest a structure for A, including its stereochemistry.