Acetal exchange reactions II. Cyclohexylidene derivatives of some glycosides and cyclitols

• Published in: Carbohydrate research 1967, Vol.5 (2), p.184-193
• Main Authors: Bissett, F.H., Evans, M.E., Parrish, F.W.
• Format: Article
• Language: English
• ISSN: 0008-6215; 1873-426X
• DOI: 10.1016/S0008-6215(00)86041-3

Reaction of various polyhydric alcohols with 1,1-dimethoxycyclohexane and p-toluenesulfonic acid in N, N-dimethylformamide produces cyclic acetals in high yield, even where these acetals bridge vicinal, trans hydroxyl groups on a six-membered ring; methyl 2,3:4,6-di- O-cyclohexylidene-α- d-glucoside and 1,2:3,4:5,6-tri- O-cyclohexylidene- scyllo-inositol are both formed in high yield by use of this reaction. Application of the reaction to methyl α- d-xylopyranoside gives a mixture of the 2,3- and 3,4- O-cyclohexylidene acetals; p-toluenesulfonylation of this mixture affords crystalline methyl 2,3- O-cyclohexylidene-4- O- p-tolylsulfonyl-α- d-xyloside in good overall yield, and a smaller proportion of methyl 3,4- O-cyclohexylidene-2- O- p-tolylsulfonyl-α- d-xyloside. The former sulfonic ester undergoes reaction with sodium benzoate in boiling N, N-dimethylformamide with change of configuration at C-4; the latter sulfonic ester does not undergo benzoate exchange. The n.m.r. spectra of the two sulfonic esters are discussed.