Are there any easy, not enzymatic, ways to hydrolyse $\beta$-1,2 glycosidic bonds like they occur in steviosids?
I thought of something like vinegar, which is commonly used to cleave the $\alpha$-1,2 glycosidic bond of saccharose when producing inverted sugar $-$ could that also work for the $\beta$-type?
Thank you in advance.
There are non-enzymatic methods for removing the three glucose moieties of stevioside 1. Unfortunately, dilute mineral acid hydrolysis not only removes the glucose entities but also effects Wagner-Meerwein rearrangement of the aglycone steviol 2 to isosteviol 3.1 While vinegar (5% aqueous acetic acid) is a weaker acid than hydrochloric acid, I am certain that it would have been tried to avoid the rearrangement of steviol 2. Exposure of stevioside 1 with aqueous KOH effects saponification of the ester group leading to steviobioside 4.---continued---
A more fruitful procedure that avoids rearrangement involves periodic acid cleavage of the five vicinal diols of the glucose units (marked in red in structure 1 below).2 This procedure liberates hexa-aldehyde 5 in addition to two equivalents of formic acid.3 Vigorous base treatment is required to saponify the hindered ester while base also liberates tetra-aldehyde entity by β-elimination forming steviol 2 in 75% yield. And NO, you can't do this at home.
1) Avent, a. G., Hanson, J. R., de Oliveira, Bras H., Phytochemistry, 1990, 29, 2712.
2) Ogawa, T., Nozaki, M., Matsui, M., Tetrahedron, 1980, 36, 2641.
3) On periodic acid cleavage of vicinal diols, see: Periodic cleavage of carbohydrates
