Boron tribromide → US10023592, Example 80
Reaction equation
B(Br)(Br)Br.[CH2:5]([S:7]([C:10]1[CH:11]=[CH:12][C:13]([O:34]C)=[C:14]([C:16]2[C:25]3[C:20](=[CH:21][CH:22]=[C:23]([C:26]4[CH:27]=[N:28][N:29]([CH3:31])[CH:30]=4)[CH:24]=3)[C:19](=[O:32])[N:18]([CH3:33])[CH:17]=2)[CH:15]=1)(=[O:9])=[O:8])[CH3:6]>C(Cl)Cl>[CH2:5]([S:7]([C:10]1[CH:11]=[CH:12][C:13]([OH:34])=[C:14]([C:16]2[C:25]3[C:20](=[CH:21][CH:22]=[C:23]([C:26]4[CH:27]=[N:28][N:29]([CH3:31])[CH:30]=4)[CH:24]=3)[C:19](=[O:32])[N:18]([CH3:33])[CH:17]=2)[CH:15]=1)(=[O:8])=[O:9])[CH3:6]Participants
4
Procedure
At −78° C., a 4 M solution of BBr3 (2.3 mL, 9.2 mmol) in CH2Cl2 was added to the title compound of Example 79 (200.0 mg, 0.458 mmol) in dry CH2Cl2 (8 mL). The mixture was refluxed for 18 h. Extractive work up with CH2Cl2 and purification by silica gel chromatography (DCM:MeOH=100:1 to 20:1) gave the title compound (70 mg, 36.1%) as a brown solid. 1H NMR (CDCl3, 400 MHz) δ 8.39 (d, J=8.4 Hz, 1H), 7.99 (s, 1H), 7.87 (dd, J1=8.8 Hz, J2=2.4 Hz, 1H), 7.80 (s, 1H), 7.79 (s, 1H), 7.76 (d, J=1.6 Hz, 1H), 7.39 (s, 1H), 7.35 (d, J=1.2 Hz, 1H), 7.18 (d, J=8.8 Hz, 1H), 3.91 (s, 3H), 3.67 (s, 3H), 3.25 (q, J=7.6 Hz, 2H), 1.27 (t, J=7.6 Hz, 3H). LCMS: 424.0 (M+H)+