tert-butyl 3-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-8-azabicyclo[3.2.1]oct-3-ene-8-carboxylate

73183-34-3

185099-68-7

900503-08-4

8-Boc-3-(trifluoromethylsulfonyloxy)-8-azabicyclo[3.2.1]oct-3-ene (10.1 g, 28.4 mmol) and pinacol ester of bis(boronic acid) (8.7 g, 34.1 mmol) were added under argon protection with KOAc (8.4 g, 85.3 mmol), PdCl2(dppf)2-CH2Cl2 ( 1.4 g, 1.7 mmol) and dppf (1 g, 1.8 mmol) in dioxane (170 ml). The reaction mixture was stirred at 80°C for 16 hours. After completion of the reaction, it was cooled to room temperature and the solvent was removed by rotary evaporation. The crude product was redissolved in EtOAc (500 ml), washed sequentially with water (125 ml) and brine (125 ml) and dried over anhydrous Na2SO4. The solvent was removed by concentration under reduced pressure and the residue was purified by silica gel column chromatography eluting with EtOAc/hexane (0-40%) gradient to afford the target product 8-tert-butoxycarbonyl-8-azabicyclo[3.2.1]oct-2-ene-3-boronic acid pinacol ester (8.6 g, 90% yield).