Glucose proton magnetic resonance spectroscopy

A feature of Horowitz and Gentili s work was the use of nuclear magnetic resonance spectroscopy. They showed that the 5 value for the benzylic proton [Hb in structure (7)], at C-1 of the D-glucose side-chain in vitexin, is virtually unchanged in the hepta-O-methyl and hepta-O-acetyl derivatives from this, it follows that the carbon atom which carries this proton cannot also carry a hydroxyl group (otherwise, acetylation would cause the signal to shift to much lower field, and methylation, to a higher field)... 

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