Diethyl Ether → [4-(6,6-Dimethyl-5,6,7,8-tetrahydroquinazolin-4-yl)-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl]boronic acid

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Reaction Conditions

Reaction Steps

To a slurry of 2,3,4,5-tetrahydro-1,4-benzoxazepin-7-ylboronic acid hydrochloride salt (5.7 g, 25 mmol) (example 8, step 1) and 4-chloro-6,6-dimethyl-5,6,7,8-tetrahydroquinazoline (reagent preparation 3) (3.0 g, 15 mmol) in dioxane (75 mL) and H2O (75 mL) was added DIPEA (17 mL, 100 mmol) and the resulting mixture was heated (90° C.). After 72 hours the solution was concentrated and partitioned between 2M aqueous sodium hydroxide and ethyl ether. The aqueous layer was neutralized and extracted with chloroform. The organic layer was washed with brine, dried over magnesium sulfate, filtered and concentrated in vacuo. Trituration with ethyl ether provided [4-(6,6-dimethyl-5,6,7,8-tetrahydroquinazolin-4-yl)-2,3,4,5-tetrahydro-1,4-benzoxazepin-7-yl]boronic acid (4.2 g, 80% yield) as a white solid. 1H NMR (400 MHz, d6-DMSO) δ 8.68 (s, 1H), 7.77 (s, 1H), 7.64 (dd, 1H), 6.86 (dd, 1H), 5.04 (s, 2H), 4.46 (m, 2H), 4.18 (m, 2H), 2.80 (t, 2H), 2.52 (s, 2H), 1.58 (t, 2H), 0.86 (s, 6H); MS (ES) for C19H24BN3O3: 354 (MH+).

Provenance & Evidence