الفهرس 
Electrophilic attack at nitrogenOnly 14 pages are availabe for public view
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Abstract
While, ethyl-6-cyano-1-(2-(2-(2-(2-(2-(2-(1-ethoxy-1-oxopropan-2-yl)hydrazinyl)-2-oxoethyl)-2H-tetrazol-5-yl)ethyl)-2H-tetrazol-5-yl)ethyl)-5-oxo-2-[(1S,2R,3S,4R)-1,2,3,4,5-pentahydroxypentyl]-7-phenyl-1,5-dihydro-[1,2,4]triazolo[1,5-a]pyridine-8-carboxylate (21) was prepared by treating of the acid hydrazide 17 with AcOH and 1N HCl and cooling at -5 oC. Sodium nitrite (NaNO2) was added and the formed ethyl-1-(2-(2-(2-(2-(2-azido-2-oxoethyl)-2H-tetrazol-5-yl)ethyl)-2H-tetrazol-5-yl)ethyl)-6-cyano-5-oxo-2-[(1S,2R,3S,4R) -1,2,3,4,5-pentahydroxypentyl]-7-phenyl-1,5-dihydro-[1,2,4]triazolo[1,5-a] pyridine-8-carboxylate (20) was treated with alanine ethyl ester in ethyl acetate containing Et3N at 0oC. The formed product was purified by recrystallization from ethanol to afford the corresponding peptide 21 in 94% yield (Scheme 19).