23.3 g (100 mmol) of 3-phenyl-quinoline-5-aldehyde are suspended in 200 ml of n-propanol and the suspension is stirred with 8.25 ml (100 mmol) of 5-methylisoxazole. A solution of 2.3 g of sodium in 100 ml of n-propanol is added dropwise and the mixture is stirred at 40°-50° C. for hours. A brown solution is obtained by this procedure. 8.04 g (100 mmol) of propyl amidinoacetate hydrochloride and 6 ml of acetic acid (100 mmol) are added and the mixture is boiled for 20 hours. It is concentrated, the residue is dissolved in ethyl acetate/water and the phases are separated. The ethyl acetate phase is washed with sodium bicarbonate solution and twice with water, dried and concentrated. The resulting residue is dissolved in 100 ml of hot acetonitrile and the product is left to crystallise. It is filtered off with suction and recrystallised from n-propanol and then from acetonitrile. 6.9 g of colourless crystals of melting point 237° C. are obtained.
