Nitrogen → 5-(4-Amino-2-nitro-phenyl)-2-methyl-furan-3-carboxylic acid methyl ester

Participants

Reaction Steps

(The following reaction is done in a N2 atmosphere.) Dissolve Pd(PPh3)4 (59 mg, 0.05 mmol) and 5-Bromo-2-methyl-furan-3-carboxylic acid methyl ester (23) (447 mg, 2.04 mmol) in DME (3 mL) and stir for 10 min at rt. Add 3-Nitro-4-(4,4,5,5-tetramethyl-[1,3,2]dioxaborolan-2-yl)-phenylamine (57) (465 mg, 1.76 mmol) followed by an aqu. 1M sodium bicarbonate solution (5.10 mL, 5.10 mmol). Degas the reaction mixture carefully, flush with N2 (5 times) and stir for 4.5 h at 90° C. (reflux). Cool reaction mixture to rt, remove organic solvent under reduced pressure and partition the residue between water and EtOAc. Extract the aqu. layer with EtOAc (3 times), wash the combined organic layer with water and brine and dry it with Na2SO4. Purify the obtained crude product by flash chromatography (silica gel, EtOAc/CyH 1+3, later 1+2) to obtain 5-(4-Amino-2-nitro-phenyl)-2-methyl-furan-3-carboxylic acid methyl ester (58) (167 mg, 34%) as a red solid. 1H NMR (400 MHz, CDCl3): 2.57 (s, 3H); 3.81 (s, 3H); 4.05 (br.s, 2H); 6.68 (s, 1 H); 6.81 (dd, 1H, J1=8.3 Hz, J2=2.3 Hz); 6.99 (d, 1H, J=2.3 Hz); 7.39 (d, 1H, J=8.3 Hz).

Provenance & Evidence