Reaktion #567394

Reaktionsgleichung

ammonia

artemisinin

2,6-di-tert-butyl-4-methylphenol

sulphuric acid

→

11-azaartemisinin

Ausbeute 45.0%

Lösungsmittel

dichloromethane

Reaktionsbedingungen

Aufarbeitung

1. 1
   Einengenconcentrated under reduced pressure
2. 2
   Sonstigeto give a light yellow solid
3. 3
   workup.STIRRINGAfter stirring overnight at room temperature
4. 4
   Filtrationthe reaction mixture was filtered
5. 5
   Waschenthe silica gel washed with dichloromethane
6. 6
   EinengenThe combined organic solution and washes were concentrated under reduced pressure

Vorschrift

To a saturated solution of methanolic ammonia (12 ml) at room temperature was added artemisinin (1.128 g, 4 mmol). The solution was stirred for 1.5 hours and concentrated under reduced pressure to give a light yellow solid. The solid was dissolved in dichloromethane (180 ml), and 2,6-di-tert-butyl-4-methylphenol (BHT) (80 mg, 0.36 mmol), 15% sulphuric acid (0.8 ml), and silica gel (8.0 g) were added in succession. After stirring overnight at room temperature, the reaction mixture was filtered and the silica gel washed with dichloromethane. The combined organic solution and washes were concentrated under reduced pressure. Column chromatography of the residue on silica gel with acetone:dichloromethane (8:92) gave crystalline solid 11-azaartemisinin (510 mg, 45%): mp 143-145° C.; Rf=0.40 (acetone:CH2Cl2, 15:85); [α]25D=−40.9° (c 0.127, CH2Cl2); IR 3313, 3223, 2928, 2873, 1668 cm−1; CIMS (NH3) 299 (M+NH4+, 76), 282 (M+1,100); 1H NMR δ 0.93-1.01 (2H, m), 0.93 (3H, d, J=5.5 Hz), 1.07 (3H, d, J=7.2 Hz), 1.30 (3H, s), 1.25-1.42 (3H, m), 1.61-1.70 (2H, m), 1.71-1.77 (1H, m), 1.92 (2H, dm, J=10.2 Hz), 2.34 (1H, m), 3.17 (1H, pent, J=6.8 Hz), 5.33 (1H, s), 5.93 (1H, bs).

Quelle