4-Methylmorpholine → 6-[(3R,9aS)-8-[2-[4-(tetrazol-1-yl)phenyl]acetyl]-3,4,6,7,9,9a-hexahydro-1H-pyrazino[2,1-c][1,4]oxazin-3-yl]-3,4-dihydroisochromen-1-one

Participants

Reaction Steps

[6-(1H-Tetrazol-1-yl)pyridine-3-yl]acetic acid (82 mg, 0.40 mmol, 1.3 eq), N-[3-(dimethylamino)propyl]-N′-ethylcarbodiimide hydrochloride (83 mg, 0.43 mmol, 1.4 eq) and 1H-1,2,3-benzotriazol-1-ol hydrate (66 mg, 0.43 mmol, 1.4 eq) were dissolved in dichloromethane (3 mL) in a 16 mL reaction vial. The mixture was stirred at r.t. for 30 min under N2. To the above mixture was added the dichloromethane solution (2 mL) of (3R,9aS)-3-(1-oxo-3,4-dihydro-1H-isochromen-6-yl)octahydropyrazino[2,1-c][1,4]oxazin-8-ium chloride (100 mg, 0.31 mmol, 1.0 eq) that was neutralized with N-methylmorpholine (34 μL, 0.31 mmol, 1.0 eq). The reaction was stirred at r.t. for 18 h, diluted with dichloromethane (10 mL), washed with saturated sodium bicarbonate solution (2×10 mL), brine (5 mL) and water (5 mL). The organic phase was dried over MgSO4, filtered and concentrated to give the crude product. The desired product was obtained after purification by flash column chromatography (0-10% MeOH/CH2Cl2) followed by preparative TLC (NH4OH/MeOH/CHCl3: 0.5:4.5:95): LC-MS (IE, m/z): [(M+1)-28]+=448.5, [(M+Na]+=498.4: 1H NMR (500 MHz, CDCl3, δ in ppm): 9.41 (1H, m), 7.99 (2H, m), 7.81 (1H, m), 7.28 (2H, m), 4.55-4.75 (1H, m), 4.45-4.55 (2H, m), 3.93 (1H, dd, J=3.2 Hz, J=11.2 Hz), 3.70-3.92 (3H, m), 3.40-3.55 (2H, m), 3.01 (2H, t, J=6.0 Hz), 2.80-3.00 (3H, m), 2.33 (1H, t, J=2.6 Hz,), 2.15-2.30 (3H, m).

Provenance & Evidence