Chemical transformation of uronic acids leading to aminocyclitols. III. Syntheses of aminocyclitols and aminocyclitol-oligoglycosides from uronic acids and glucuronide-saponins by means of electrolytic decarboxylation.

Abstract

Conversions of uronic acids [e.g. methyl 2, 3, 4-tri-O-methyl-β-D-glucopyranosiduronic acid (1), D-glucuronic acid (9), and D-galacturonic acid (17)] into the corresponding aminocyclitols [e.g. 6b, 7b, 8b ; 14b, c, 15b, c, 16b, c ; 18b] have been accomplished by means of initial electrolytic decarboxylation and subsequent treatment with alkaline nitromethane, followed by catalytic reduction, and acetylation. The conversion method has also been applied to neutral sugar [e.g. D-mannose (19)] to affording L-neo-aminocyclitol hexaacetate (22b) and also to two glucuronide-saponins [sakuraso-saponin (23) and desacyl-jegosaponin (27)] to afford aminocyclitol-oligoglycosides (26a, 28a). The present electrolytic conversion is noteworthy since prior protection of hydroxyl groups in the starting uronic acids is not necessary.