Diisopropylethylamine → tert-butyl 6-oxo-1,2,4a,5,6,7-hexahydropyrazino[1,2-a][1,5]benzodiazepine-3(4H)-carboxylate

Participants

Reaction Steps

The product of Example 22C (658 mg, 1.801 mmol) was dissolved in methanol (50 mL) and 10% Pd/C (52 mg) was added. The flask was evacuated and purged with nitrogen (3 cycles) and then with hydrogen (3 cycles), and the reaction was stirred at room temperature under hydrogen (1 atm) for 7 hours. The flask was evacuated and purged with nitrogen (3 cycles), and the reaction mixture was filtered through a pad of diatomaceous earth. The filtrate was concentrated under vacuum, and the residue was dissolved in tetrahydrofuran (25 mL). O-(7-Azabenzotriazol-1-yl)-N,N,N′,N′-tetramethyluronium hexafluorophosphate (680 mg, 1.788 mmol) and diisopropylethylamine (1 mL) were added, and the mixture was stirred at room temperature for 14 hours and then concentrated under vacuum. The residue was purified by chromatography (SiO2, eluted with hexanes-ethyl acetate, 100:0-50:50) to provide the title compound: 1H NMR (300 MHz, CDCl3) δ ppm 1.48 (s, 9H), 2.18 (d, J=13.5 Hz, 1H), 2.74 (dd, J=13.3, 6.9 Hz, 1H), 2.88-3.30 (m, 5H), 4.01-4.19 (m, 2H), 6.93-6.98 (m, 1H), 7.01-7.10 (m, 2H), 7.16 (s, 1H), 7.17-7.24 (m, 1H); MS (DCI) m/z 318 (M+H)+.

Provenance & Evidence