A mixture of 3A (1.46 g, 6.9 mmol) and 3-nitrobromobenzene (0.81 g, 4.0 mmol) in DME (40 mL) and 2.0 M Na2CO3 (8.0 mL) was degassed by bubbling argon for 5 min. To this solution, Pd(PPh3)4 (280 mg, 0.25 mmol) was added. The mixture was heated at 90° C. for 5 h. After cooling to rt, it was extracted with EtOAc and dried over Na2SO4. The product was purified by silica gel chromatography (CH2Cl2/hexanes=1/5) to give 4A (880 mg, 75% yield) as viscous oil. 1H NMR (400 MHz, Methanol-d4) δ ppm 1.37 (s, 9H) 6.28 (t, J=3.52 Hz, 1H) 6.33 (dd, J=3.52, 1.76 Hz, 1H) 7.41 (dd, J=3.52, 1.76 Hz, 1H) 7.59 (m, 1H) 7.73 (d, J=7.91 Hz, 1H) 8.16 (m, 2H).
