A practical synthesis of ethyl 1,2,4-triazole-3-carboxylate and its use in the formation of chiral 1′,2′-seco-nucleosides of ribavirin

A practical and efficient synthesis of ethyl 1,2,4-triazole-3-carboxylate ( 6a , R' = H) from ethyl carboethoxyformimidate hydrochloride ( 7 ) is described. Alkylation of this heterocycle with the chloromethyl ethers of 1,3-O-dibenzylbutane-1,2R,3S-triol ( 8a ) and 1,3,4-O-tribenzylbutane-1,2R,3S,4-tetrol ( 8b ), followed by conversion of the ester function to the amide and deprotection, furnished the chiral 1′,2′-seco-nucleosides of ribavirin, 11a and 11b , respectively.