81.6% |
With hydrogen In ethyl acetate |
1 Methyl 4-amino-1-methyl-pyrrole-2-carboxylate hydrochloride
Methyl 4-amino-1-methyl-pyrrole-2-carboxylate hydrochloride Methyl-4-nitropyrrole-2-carboxylate 4 (450 g, 2.8 mol) was dissolved in ethyl acetate (8 L). A slurry of 40 g of 10% Pd/C in 800 mL ethyl acetate was then added and the mixture stirred under a slight positive pressure of hydrogen (c.a. 1.1 atm) for 48 h. Pd/C was removed by filtration through celite, washed 1*50 mL ethyl acetate, and the volume of the mixture reduced to c.a. 500 mL. 7 L of cold ethyl ether was added and HCI gas gently bubbled through the mixture. The precipitated amine hydrochloride was then collected by vacuum filtration to yield a white powder (380 g, 81.6%). |
|
With hydrogen In ethyl acetate |
(xiii)
Methyl 4-amino-1-methyl-pyrrole-2-carboxylate hydrochloride (B-3). Compound B-2 (450g, 2.8 mol) was dissolved in ethyl acetate (8 L). A slurry of 40 g of 10% Pd/C in 800 mL ethyl acetate was then added and the mixture stirred under a slight positive pressure of hydrogen (c.a. 1.1 atm) for 48 h. Pd/C was removed by filtration through Celite, washed 1*50 mL ethyl acetate, and the volume of the mixture reduced to c.a. 500 mL. 7 L of cold ethyl ether was added and HCI gas gently bubbled through the mixture. The precipitated amine hydrochloride was then collected by vacuum filtration to yield (380 g, 81.6 %) of methyl 4-amino-1-methyl-pyrrole-2-carboxylate hydrochloride (shown as compound B-3 in Scheme B) as a white powder. TLC (ethyl acetate) Rf(amine) 0.6, Rf salt (0.0), 1H NMR (DMSO-d6) δ 10.23 (br s, 3H), 7.24 (d, 1H J=1.9), 6.79 (d, 1H, J=2.0), 3.83 (s, 3H), 3.72 (s, 3H) 13C NMR (DMSO-d6) δ 160.8, 124.3, 121.2, 113.4, 112.0, 51.8, 37. 1; IR (KBr) 3095, 2693, 1709, 1548, 1448, 1266, 1102, 802, 751. FABMS m/e 154.075 (154.074 calc. for C7H10N2O2). |