Preparation of C-(2-deoxyhex/pent-1-enopyranosyl)heterocycles

Acetylated 1-cyanoglycals (2,6-anhydro-3-deoxyhept/hex-2-enononitriles) were prepared by direct elimination of acetic acid from the appropriate acetylated 2,6-anhydrohept/hexononitriles with 1,3-di-azabicyclo[5.4.0]undec-7-ene (DBU) in aprotic solvents. Heterocyclisation of the cyano group of acetylated 1-cyano- d -galactal with 2-aminothiophenol led to 2-(3,4,6-tri- O -acetyl-2-deoxy- d - lyxo -hex-1-enopyranosyl)benzothiazole. Several 2-(per- O -acetylhexo/pentopyranosyl)benzothiazoles also gave 2-(per- O -acetyl-2-deoxyhex/pent-1-enopyranosyl)benzothiazoles with DBU. 3-(Per- O -acetylhexo/pentopyranosyl)-[1,2,4]triazolo[4,3- a ]pyrimidines rearranged with DBU to the corresponding acetylated 2-glycosyl-[1,2,4]triazolo[1,5- a ]pyrimidines. By the reaction of 1-cyano- d -galactal with ammonium azide, 2-(3,4,6-tri- O -acetyl-2-deoxy- d - lyxo -hex-1-enopyranosyl)tetrazole was prepared and then transformed with carboxylic acid derivatives into 2-(3,4,6-tri- O -acetyl-2-deoxy- d - lyxo -hex-1-enopyranosyl)-5-substituted-1,3,4-oxadiazoles.