Microsynthesis of Dianhydrohexitols

Homo-C-nucleoside analogs III. Studies on the base-catalyzed dehydrative cyclization of 4-(d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole

Treatment of 4-(d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole with one molar equivalent of 2,4,6-triisopropylbenzenesulfonyl chloride (TIBSCl) in pyridine solution afforded the homo-C-nucleoside analog; 4-(2,5-anhydro-d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole in 54% yield and 4-(α-d-arabinopyranosyl)-2-phenyl-2H1,2,3-triazole analog in 3% yield. The 4-(5-O-triisopropylbenzenesulfonyl)-d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole analog was isolated as an intermediate and identified as its tetra-O-acetyl derivative. The 4-(5-chloro-5-deoxy-d-manno-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole analog was isolated as a byproduct. The structure and anomeric configuration of the products were determined by acylation, NMR spectroscopy, and mass spectrometry.

The solvent-free thermal dehydration of hexitols on zeolites

Dehydration of galactitol, D-glucitol and D-mannitol at high temperature in the presence of molecular sieves without solvent under an argon atmosphere is described. Cyclodehydration products with retention or inversion of the configuration at asymmetric carbon atoms, were observed. Reaction of galactitol yielded racemic 1,4-anhydrogalactitol in a first step and then racemic 1,4:3,6-dianhydroiditol. Complete analytical separations of exhaustively O-acetylated reaction products were achieved by GC and structures were assigned using co-injection with standards.