Hydrochloric Acid → HCID 19592033, compound

Participants

Reaction Steps

A suspension of the acid 266 (1.32 g, 3.58 mmol) in dry ether (37 ml) was treated with phosphorus pentachloride (1.04 g, 5 mmol) and stirred at room temperature for 2 h. The solution was filtered to remove unreacted phosphorus pentachloride then evaporated to dryness. The residue was treated with dry toluene (25 ml) then evaporated to dryness. This process was repeated several times. The resulting oil was dissolved in dry dichloromethane (25 ml), cooled to 0° C. and treated with a solution of (3S) t-butyl 1-benzyloxycarbonylpyridazine-3-carboxylate (1.15 g, 3.58 mmol) in dry dichloromethane (2 ml) followed by 5% aqueous sodium bicarbonate solution (25 ml). The mixture was stirred rapidly at room temperature for 20 h then diluted with ethyl acetate (100 ml) and acidified to pH2 with 1M HCl. The organic phase was washed twice with dilute HCl solution then brine, dried (MgSO4) and concentrated. The resulting oil was purified by flash chromatography (2-20% ethyl acetate/dichloromethane then 10-20% methanol/dichloromethane) to afford (267), 1.25 g (52%) as a white powder: IR (KBr) 3367, 2955, 1722, 1517, 1455, 1387, 1369, 1251, 1153, 721; 1H NMR (CDCl3) δ 7.81 (2H, m), 7.74 (2H, m), 7.63 (1H, brs), 7.31 (10H, m), 5.46-4.76 (5H, m), 4.07-3.54 (4H, m), 2.4 (1H, m), 2.0-1.6 (3H, m), 1.40 (9H, s); MS (ES+), 671 (M+1), 693 (M+Na).

Provenance & Evidence