Syntheses with anhydro sugars : Part IX. 1,6-anhydro-2,4- DI- O-toluene- p-sulphonyl-β- D-hexopyranos-3-uloses and related compounds

Abstract

P.m.r., i.r., and u.v. spectral data establish that 1,6-anhydro-2,4-di- O-toluene- p-sulphonyl-β- D-hexopyranos-3-uloses exist in chair conformations in chloroform solution. The signals for axial protons α to the carbonyl group appear at τ values that are lower than those for the corresponding equatorial protons. The i.r. and u.v. absorption frequency of the carbonyl group of the tosylated ketones is dependent on the position of the sulphonyloxy group in a manner analogous to that for α-halogeno ketones. The c.d. spectra of these compounds do not accord with predictions based on the octant rule. The tosylated ketones in chloroform solution are isomerised by the action of 5% of pyridine.