To a mixture of 1-methyl-1,2,3,6-tetrahydropyridin-4-yl trifluoromethanesulfonate 257 (450 mg, 1.84 mmol), bis(pinacolato)diboron (477 mg, 2.02 mmol) and K2CO3 (541 mg, 5.52 mmol) in DME (3.7 mg), Pd(PPh3)4 (106 mg, 0.092 mmol) was added in one portion and the system was heated to reflux for 2 h under N2. The reaction mixture was cooled down and filtered. To the filtrate containing the intermediate 258 were added bromide 50 (435 mg, 1.84 mmol), CsF (838 mg, 5.52 mmol), NaHCO3 (463 mg, 5.52 mmol) and water (0.8 mL), and the mixture was heated to reflux for 2 h more. The reaction mixture was diluted with water and extracted with DCM; the organic phase was extracted with 1N HCl, the aqueous phase basified to pH-11 by addition of 2N aqueous NaOH, extracted with DCM, dried over anhydrous Na2SO4 and concentrated under reduced pressure affording 259 (279 mg, 0.72 mmol, 39% yield) as a brown solid. MS (m/z): (M+1) 385.9 (100%).
