A mixture of 140 mg (0.20 mmol) (R)-1-(4-amino-3-chloro-5-trifluoromethyl-benzyl)-2-oxo-2-(4-piperidin-4-yl-piperazin-1-yl)-ethyl 4-(2-oxo-1,2,4,5-tetrahydro-1,3-benzodiazepin-3-yl)-piperidine-1-carboxylate (Example 29a), 60.8 mg (0.44 mmol) K2CO3 and 45 μL (0.30 mmol) ethyl 2-bromo-2-methyl-propionate in 1.8 mL DMF was shaken at 50° C. for 12 h and then for 48 h at RT. The precipitate was filtered off and the filtrate was purified by HPLC without working up; the fractions containing the product were combined, evaporated down i. vac., the residue was made alkaline with saturated NaHCO3 solution, the precipitate was suction filtered, washed with 20 mL water and dried at 40° C.
