2-(difluoromethyl)-5-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyridine synthesis

Yield: 89%

Reaction Conditions:

with (1,1'-bis(diphenylphosphino)ferrocene)palladium(II) dichloride;potassium acetate in 1,4-dioxane at 20 - 100; for 1 h;Inert atmosphere;

Steps:

Intermediate 249A: 2-(difluoromethyl)-5-(4,4,5,5-tetramethyl-1 ,3,2-dioxaborolan-2-yl)- pyridine
To a solution of 5-bromo-2-(difluoromethyl)pyridine (1.0 g, 4.8 mmol) and bis(pinacolato)diboron (1.34 g, 5.3 mmol) in dioxane (5 mL) was added potassium acetate (1.4 g, 14.4 mmol) at room temperature. Nitrogen gas was bubbled through the mixture for 5 mins and 1 ,1 '-bis(diphenylphosphino)ferrocenepalladium(ll) chloride (264 mg, 0.36 mmol) was then added. The mixture was heated at 100 °C for 1 hour. The reaction mixture was then diluted with EtOAc (50 mL), filtered over Celite and washed with EtOAc (50 mL). The filtrate was concentrated at reduced pressure and the residue was purified by Biotage Isolera chromatography [SNAP Cartridge KP-Sil 50 g; 0-100% EtOAc in heptane, 16 column volumes]. The product containing fractions were combined and concentrated in vacuo to afford the title compound (1.15 g, 89% yield) as pale yellow crystalline solid.¹H NMR (500 MHz, Chloroform-d) δ [ppm] 8.97 (s, 1 H), 8.21 (dd, J = 7.7, 1 .4 Hz, 1 H), 7.62 (d, J = 7.7 Hz, 1 H), 6.64 (t, J = 55.4 Hz, 1 H), 1.36 (s, 12H).LCMS (Analytical Method A): Rt = 0.78 mins, MS (ESIpos) m/z = 173.9 (Mass of boronic acid + H)

References:

BAYER PHARMA AKTIENGESELLSCHAFT;BÄURLE, Stefan;DAVENPORT, Adam, James;STIMSON, Christopher;CARR, James, Lindsay;BUBERT, Christian, Abingdon;MARLIN, Frédéric, Jacques;NAGEL, Jens;SCHMIDT, Nicole;ROTGERI, Andrea;IRLBACHER, Horst WO2018/114783, 2018, A1 Location in patent:Page/Page column 189