Sucrochemistry : Part VI. Further reactions of 6,6′- DI- O-tosylsucrose and a comparison of the reactivity at the 6 and 6′ positions

Abstract

Reaction of 6,6′-di- O-tosylsucrose hexa-acetate ( 1) with sodium chloride in hexamethylphosphoric triamide gave a mixture containing preponderantly the hexa-acetates of 6,6′-dichloro-6,6′-dideoxysucrose ( 2) and 6-chloro-6-deoxy-6′- O-tosyl-sucrose ( 3). Reaction of 3 with sodium benzoate in (Me 2N) 3PO gave the 6-chloro-6-deoxy-6′- O-benzoyl derivative 4. Subsequent O-de-esterification afforded syrupy 6-chloro-6-deoxysucrose ( 5), which gave a crystalline heptamethanesulphonate. The chloro groups in the heptabenzoate 7 and the hexa-acetate 2 were replaced by azide in (Me 2N) 3PO to give the corresponding derivatives of 6-azido-6-deoxysucrose ( 12) and 6,6′-diazido-6,6′-dideoxysucrose ( 8), respectively. O-De-esterification of the hexa-acetates 2 and 8 yielded the parent 6,6′-dichloride 6 and 6,6′-diazide 9, respectively. 6,6′-Di- O-tosylsucrose hexabenzoate ( 10) reacted with sodium bromide in (Me 2N) 3PO to give the 6,6′-dibromide 11, in high yield, which afforded 6-deoxy-β- D- xylo-hex-5-enopyranosyl 6′-deoxy-β- D- threo-hex-5′-enofuranoside hexabenzoate on treatment with silver fluoride in pyridine.