A solution of 2-ethyl-4-[(2'-(2-tributylstannyl-2H-tetrazol-5-yl)biphenyl-4-yl)methoxy]quinoline in toluene (15 ml), prepared in situ by refluxing for 90 hours a mixture of 4'-[(2-ethylquinolin-4-yloxy)methyl]biphenyl-2-carbonitrile (0.9 g) and a solution of tributyltin azide in toluene (15 ml) [the latter prepared by reaction of tributyltin chloride (3.3 g) and sodium azide (1.13 g) in water (22.5 ml) at ambient temperature for 4 hours, followed by extraction with toluene and azeotropic removal of water from the extract to leave a volume of 15 ml], was added slowly over 1 hour to a solution of sodium nitrite (2.5 g) in water (10 ml) containing 12% w/v hydrochloric acid (10 ml), maintaining the temperature of the mixture below 5° C. A solution of sulphamic acid (1.43 g) in water (10 ml) was then added, maintaining the temperature below 5° C., and the mixture stirred for 1 hour. The resultant suspended semi-solid was collected by filtration and washed with water (3×10 ml), followed by toluene (10 ml). The semi-solid was then added to tetrahydrofuran (THF) (40 ml), which caused the product to dissolve and then crystallise as a white solid. After cooling for one hour the solid was collected by filtration, washed with THF (5 ml) and dried to give 2-ethyl-4-[(2'-(1H-tetrazol-5-yl)biphenyl-4-yl)methoxy]-quinoline hydrochloride; NMR similar to the product obtained from Example 10.
