A mixture of 32 g (0.108 mole) of 3-[5'-(3"- bromophenyl)-2'Htetrazole]
propionic acid and 80 g of thionyl chloride in 250 ml of dry
chloroform was stirred under reflux for 16 hours. Evaporation of the solvent
and excess reagent under reduced pressure gave a tan oil which was
redissolved in 300 ml of dry tetrahydrofuran. To this was added 20 ml of
redistilled piperidine in 100 ml of dry tetrahydrofuran. The mixture was stirred
for 15 min at room temperature. The tetrahydrofuran was then removed
under reduced pressure and the residue well triturated with one liter of 0.1 N
hydrochloric acid. The resulting semi-solid was taken up in 700 ml of ether
and extracted with 300 ml of 3% aqueous sodium bicarbonate solution. The
ether solution was then dried over calcium chloride, filtered, and cooled in the
refrigerator. This deposited 25 g (69 %) of tan needles of N-3-[5'-(3"-
bromophenyl)-2'H-tetrazole]propionyl piperidine; melting point 69°C.
