0.107 g (2 mmol) of ammonium chloride, 0.328 g (1 mmol) of TOTU and 0.517 g (4 mmol) of N,N-diisopropylethylamine are added, at ambient temperature under an inert atmosphere, to 0.233 g (0.5 mol) of 3-{3-[(2-methyl-4-oxo-3-propyl-3,4-dihydroquinazolin-6-yl)carbonyl]imidazo[1,5-a]pyridin-1-yl}benzoic acid in 30 ml of DMF. The reaction medium is stirred for 5 hours at ambient temperature and then concentrated under reduced pressure. 50 ml of a saturated solution of sodium hydrogen carbonate are added to the residue. The precipitate obtained is filtered off, and then dried under reduced pressure at 50° C. overnight. 0.230 g of a yellow solid is obtained.
