ALKALINE DEGRADATION OF 1,5-ANHYDRO-4-O-β-D- GLUCOPYRANOSYL-2,3,4-TRI-O-METHYL-D-GLUCITOL

摘要

The title compound (2) was degraded at 150-180℃ in oxygen-free 0.5-2.5M aqueous NaOH. Degradation occurred by cleavage of both the glycosyl-oxygen bond (80-95%) and the oxygen-aglycon bond (5-20%). Cleavage of the glycosyl-oxygen bond yielded 1,5-anhydro-2, 3, 6-tri-O-methyl-D-glucitol (5) from the aglycon. The reactive intermediate, 1, 6-anhydro-β-D-glucopyranose, was formed from the glycosyl moiety in amounts (50-88%) dependent upon the reaction conditions. Cleavage of the oxygen-aglycon bond resulted in unidentified products, probably acidic and fragmentary in nature and quantified as a mass deficit. Data for cleavage of the glycosyl-oxygen bond is consistent with an S_NicB(2′) mechanism while that for oxygen-aglycon bond cleavage is consistent with an S_N1 mechanism.