To 21B (0.53 g, 2.0 mmol), 3A (0.51 g, 2.4 mmol) and sodium carbonate (4.0 mL, 2M, 8.0 mmol) in 1,2-dimethoxyethane (25 mL, flushed and degassed (3×) with nitrogen) was added Pd(PPh3)4 (0.23 g, 0.2 mmol) under nitrogen. The reaction was heated to 95° C. for 3 h. The catalyst was filtered over celite and washed with ethyl acetate. The organic layer was washed with water, brine and then dried over sodium sulfate. The solvent was removed and the crude residue was purified by flash column chromatography to give 0.58 g of product 21C (69% yield).
