反应详情

(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 (39) (465 mg, 1.76 mmol) followed by an aqu. 1 M 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 (40) (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, 1H); 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).

1. custom(The following reaction
2. customDegas the reaction mixture carefully
3. customflush with N2 (5 times)
4. stirringstir for 4.5 h at 90° C.
5. temperature(reflux)
6. temperatureCool
7. customreaction mixture to rt
8. customremove organic solvent under reduced pressure
9. custompartition the residue between water and EtOAc
10. extractionExtract the aqu
11. washlayer with EtOAc (3 times), wash the combined organic layer with water and brine
12. dry with materialdry it with Na2SO4
13. customPurify the
14. customobtained crude product by flash chromatography (silica gel, EtOAc/CyH 1+3, later 1+2)