An oven-dried, 1-L, 3necked flask was equipped with Teflon-coated magnetic stirring bar, reflux condenser, and argon inlet. The apparatus was flushed with Ar for 30 minutes. The flask was charged with 3 (10.0 g, 27.2 mmol), Pd(OAc)2 (143 mg, 0.64 mmol), 2-dicyclohexylphosphino-2′-(N,N-dimethylamino)biphenyl (490 mg, 1.23 mmol), sodium tert-butoxide (9.4 g, 98 mmol), and benzophenone hydrazone (9.6 g, 49.0 mmol). The apparatus was purged for 5 more minutes with Ar and then placed under a static Ar atmosphere (balloon). Toluene (120 mL) was added via cannula and stirring initiated. The resulting mixture was placed in an 80° C. oil bath (external temperature) for 20 h. The reaction mixture was allowed to cool to ambient temperature, and the toluene was removed in vacuo. The crude product was dissolved in 200 mL acetonitrile and filtered through a pad of silica gel (150 g in a 350 mL fritted funnel). The plug was washed with 6×100 mL acetonitrile then 10×100 mL MeOH. The product containing fractions were combined and concentrated to produce a red solid, which was dissolved in hot EtOH (30 mL) and treated with hexanes (20 mL) to induce crystallization. The flask was cooled to ambient temperature and then placed in an ice bath for 1 h. The resultant solid (4) was collected by filtration and washed with cold hexanes (2×30 mL) to provide 13.75 g (76% yield).
