To a solution of 20% phosgene in toluene (0.49 mL, 0.93 mmol) was added a solution of tert-butyl (3S)-3-aminopyrrolidine-1-carboxylate (38 mg, 0.20 mmol) and triethylamine (102 μL, 0.734 mmol) in THF (0.5 mL). The resulting solution was stirred for 2 hours then concentrated. To the isolated solids was added DCM (0.75 mL) followed by 6-chloro-2,4,8,18,22-pentaazatetracyclo[14.3.1.1(3,7).1(9,13)]docosa-1(20),3(22),4,6,9(21),10,12,16,18-nonaen-12-amine bis(trifluoroacetate) (70 mg, 0.1 mmol) and triethylamine (73 μL, 0.52 mmol). The resulting mixture was stirred at room temperature overnight and concentrated. The residue was purified by flash column chromatography to yield the desired product (34 mg, 50%). LCMS calculated for C27H32ClN8O3(M+H)+: m/z=551.1.
