16.74 g (80 mmol) of the “4-hydroxymethyl-biphenyl-2-carbonitrile” is suspended in 100 ml of dry xylene (isomer mixture) under argon. To this suspension is added at room temperature under stirring 0.636 g (80 mmol) of lithium hydride. The suspension is stirred for an additional 4 hours at 120° C. external temperature and a solution of 160 mmol diethylaluminium azide in toluene (which is prepared separately by stirring 160 mmol of diethylaluminium chloride and 160 mmol of sodium azide in xylene [isomer mixture] at room temperature overnight) is added via syringe. The reaction mixture is heated to reflux (˜120° C.), external temperature ca. 140° C. Conversion is controlled by HPLC analysis. After refluxing for 24 hours the reaction mixture is cooled to room temperature and finally quenched with a solution of 300 mmol of sodium nitrite and of 15% sodium hydroxide (240 mmol). Finally 95 ml of conc. HCl is added under stirring. To the resulting suspension is added at room temperature under stirring 31 g (320 mmol) of 65% nitric acid. The suspension is stirred for an additional 6 hours at 60° C. external temperature (internal Temperature=55° C.). Finally the product is isolated by filtration. The crude 2′-(1H-tetrazol-5-yl)-biphenyl-4-carbaldehyde is obtained.
