To a room temperature solution of tert-butyl methyl((S)-1-((2S,3S)-2-methyl-4-oxo-1-(tetrahydro-2H-pyran-4-carbonyl)-2,3,4,5-tetrahydro-1H-benzo[b][1,4]diazepin-3-ylamino)-1-oxopropan-2-yl)carbamate (prepared as in Example RK-1, Step 3, 75 mg, 154 μmol) in N,N-dimethylformamide (500 μl) was added 1-(chloromethyl)-2-methoxynaphthalene (38 mg, 184 μmol), cesium carbonate (65 mg, 200 μmol), and sodium iodide (30 mg, 200 μmol). The reaction was stirred at room temperature for 16 h. After this time, the reaction mixture was diluted with ethyl acetate (20 mL), washed with water (20 mL) the aqueous layer was then extracted with ethyl acetate (2×20 mL) and the organic layers combined and then washed with a saturated aqueous sodium chloride solution (30 mL), dried over magnesium sulfate, filtered, and the filterate concentrated in vacuo. The crude material was purified by flash chromatography to afford tert-butyl(S)-1-((3S,4S)-1-((2-methoxynaphthalen-1-yl)methyl)-4-methyl-2-oxo-5-(tetrahydro-2H-pyran-4-carbonyl)-2,3,4,5-tetrahydro-1H-benzo[b][1,4]diazepin-3-ylamino)-1-oxopropan-2-yl(methyl)carbamate (53 mg, 52%) as a light yellow foam: LC-MS m/z 681 [M+Na]+.
