[C:1]([C:3]1[N:4]([NH:8]C(=O)OC(C)(C)C)[CH:5]=[CH:6][CH:7]=1)#[N:2].O1CCOCC1.[ClH:22].O1CCOCC1.CCOC(C)=O.CCCCCC>C(OCC)C>[ClH:22].[NH2:8][N:4]1[CH:5]=[CH:6][CH:7]=[C:3]1[C:1]#[N:2]
A 3 L, 3-neck RB flask was fitted with a mechanical stirrer, nitrogen inlet, thermocouple/JKEM thermocontroller, addition funnel and ice water cooling bath. (2-Cyano-pyrrol-1-yl)-carbamic acid, tert-butyl ester (85 g, 0.41 mol) was added and dissolved with 1,4-dioxane (400 mL), then the stirred orange solution was cooled to 0° C. and HCl/dioxane (4N, 820 mL, 8 eq.) was slowly added from the addition funnel, maintaining an internal temperature below 5° C. After ˜30 minutes the solution became cloudy and stirring @ room temperature was continued for 5 hours; the reaction was monitored for completion by TLC (silica gel, GHLF, 1:3 EtOAc/hexane, UV; Note: the free base may be observed as a high-Rf spot and can be misinterpreted as incomplete reaction). The reaction mixture was diluted with diethyl ether (2 L) and the precipitated solids were collected by suction filtration and washed with ether (1 L). Drying (vacuum oven @ 50° C.) afforded the desired product as 50.5 g (85%) of a tan solid. 1H-NMR (CD3OD): δ 7.05 (dd, 1H, J=2.8, 1.9 Hz), 6.75 (dd, 1H, J=1.8, 4.2 Hz), 6.13 (dd, 1H, J=2.8, 4.4 Hz), 5.08 (s, 3H, NH3+); MS: GC/MS, m/z=1082 [M+H].
Wird geladen…
