129090-64-8 2,3-Digsp 26784-78-1 Methyl 2,3-4,5-di-O-isopropylidine-alpha-glucoseptanoside Methyl 2,3-4,5-di-O-isopropylidine-glucoseptanoside alpha-D-Glucoseptanoside, methyl 2,3:4,5-bis-O-(1-methylethylidene)-