07 d j 1 76 hz 1h 7 59 d j 8 51 hz 1h 7 43 s 1h 6 98 d j 1 76 hz 1h 6 73 dd j 8 51 1 91 hz 1h 6 06 br s 2h 5 11 br s 2h to the solution of 5 bromo 3 cyanopyridine 3 0 g 15 9 mmol 1 eq in anhydrous dimethylformamide 40 ml was added ammonium chloride 1 45 g 1 7 eq and sodium azide 1 76 g 1 7 eq the resulting reaction mixture was heated at 100 u00b0 c under nitrogen for 20 hours after the reaction mixture was cooled to room temperature it was poured into ice water and the ph of the mixture was adjusted to u02dc 3 5 using aqueous hydrochloric acid 2 n the aqueous was first extracted with ethyl acetate three times followed by an extraction with i proh u2014 chcl 3 1 4 all organics were combined and dried with anhydrous sodium sulfate the upper clear liquor was decanted concentrated under reduced pressure and the resulting oily residue was placed under high vacuum for 20 hours upon treatment with etoac hex 1 1 and filtration 3 bromo 5 2h tetrazol 5 yl pyridine was obtained as a white solid in the amount of 3 241.