Br[CH:2]([C:23]1[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1)[C:3]([C:5]1[CH:10]=[CH:9][C:8]([C:11]2([NH:15][C:16](=[O:22])[O:17][C:18]([CH3:21])([CH3:20])[CH3:19])[CH2:14][CH2:13][CH2:12]2)=[CH:7][CH:6]=1)=O.[NH2:29][C:30]1[N:31]=[N:32][C:33]([Br:37])=[CH:34][C:35]=1[Br:36].C(N(CC)C(C)C)(C)C>C(O)(C)C>[C:23]1([C:2]2[N:31]3[N:32]=[C:33]([Br:37])[CH:34]=[C:35]([Br:36])[C:30]3=[N:29][C:3]=2[C:5]2[CH:6]=[CH:7][C:8]([C:11]3([NH:15][C:16](=[O:22])[O:17][C:18]([CH3:19])([CH3:21])[CH3:20])[CH2:12][CH2:13][CH2:14]3)=[CH:9][CH:10]=2)[CH:28]=[CH:27][CH:26]=[CH:25][CH:24]=1A mixture of crude tert-butyl (1-{4-[bromo(phenyl)acetyl]phenyl}cyclobutyl)carbamate that was prepared in a manner analgous to that described for Intermediate Example Int-1-A (5.80 g, 13.1 mmol), 3-amino-4,6-dibromopyridazine (CAS Registry No. 1206487-35-5, 3.96 g, 15.7 mmol, 1.2 eq), N,N-diisopropylethylamine (2.3 mL, 13.0 mmol, 1.0 eq) and powdered activated 3 Å molecular sieves (10 g) in isopropanol (70 mL) was heated at the reflux temperature for 8 h. On cooling, the mixture was filtered through a pad of Celite. The Celite was washed with DCM, and the combined organics were washed with water, dried with sodium sulfate and concentrated under reduced pressure. The remaining material was purified using MPLC (Biotage Isolera; 100 g SNAP cartridge: 100% hexane 2.0 min., gradient to 75% hexane/25% EtOAc 2.5 min., 75% hexane/25% EtOAc 4.5 min., gradient to 50% hexane/50% EtOAc 2 min., 50% hexane/50% EtOAc 4.5 min., gradient to 100% EtOAc 2.5 min., 100% EtOAc 5.7 min.) to give partially purified tert-butyl (1-{4-[3-phenyl-6,8-dibromoimidazo[1,2-b]pyridazin-2-yl]phenyl}cyclobutyl)carbamate (2.65 g, ˜82% pure, 28% yield):
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