Acetylenic sugar derivatives from glycals

Abstract

D- lyxo-5-Hexyne-1,2,3,4-tetrol (II) was synthesized by reaction of 3,4,6-tri- O-acetyl-2-bromo- D-glucal (I) with butyllithium. Compound I was made from tri- O-acetyl- D-glucal via its dibromo adduct and treatment with triethylamine. The α- D- gluco form of the dibromo adduct is regarded as being the active participant in the dehydrobromination. D- threo-4-Pentyne-1,2,3-triol was similarly prepared from di- O-acetyl- D-xylal. II was acetylated to its tetraacetate (II-Ac), and hydrogenated to D- lyxo-1,2,3,4-hexanetetrol. II-Ac was hydrogenated to the hexanetetrol tetraacetate, which exhibited dimorphism. Ozonolysis gave tetra- O-acetyl- D-arabinonic acid and thus provides a new general method for preparing fully acetylated aldonic acids. The CCH part of II-Ac was readily hydrated to COCH 3, thus yielding an acyclic ketose derivative; but conditions were not found for effecting oxidative coupling of the copper(I) acetylide. Saponification of II-Ac (to II) was not accompanied by further cleavage of II into acetylene and D-erythrose. Lithium aluminum hydride converts 2,3-dibromotetrahydropyran into 3-bromotetrahydropyran, and changes the dichloride of tri- O-acetyl- D-glucal to 1,5-anhydro-2-chloro-2-deoxy- D-glucitol (and -mannitol). In the reduction of tetra- O-acetyl-α- D-glucopyranosyl bromide to tri- O-acetyl- D-glucal, some samples of zinc dust gave excellent yields, whereas other samples failed completely, even in the presence of some favored promoters.