A solution of 21 (100 mg, 0.507 mmol) and 2 (84 mg, 0.507 mmol) in toluene and ethanol (4:1 mL) was added Na2CO3 (111.01 mg, 1.014 mmol). The reaction was degassed and purged with nitrogen for 10 min. Pd(dppf)Cl2 (20.7 mg, 0.025 mmol) was added to the reaction. The reaction was degassed and purged with nitrogen for another 10 min. The reaction was heated to 90° C. under sealed condition overnight, allowed to cool to RT, and diluted with chloroform. The organic layer was filtered through Celite and concentrated to get the crude, which was purified through flash chromatography by using 100-200 mesh silica gel. The compound was eluted in 40% ethyl acetate in hexane as an off-white solid 22. MS-ES+264.8; 1H NMR (400 MHz, DMSO-D6) 22: 9.99 (bs, 1H), 9.40 (bs, 1H), 7.25 (bs, 1H), 7.08 (m, 1H), 7.00 (d, 1H), 6.42 (m, 2H), 6.21 (m, 1H), 5.71 (m, 1H).
