Catecholborane → (S)-isopropyl 2-(5-bromo-4-(3,3-difluoroazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-hydroxyacetate

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The 0.33 mL of benzo[d][1,3,2]dioxaborole (166 mg, 1.38 mmol) was added to a nitrogen purged solution of isopropyl 2-(5-bromo-4-(3,3-difluoroazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-oxoacetate (360 mg, 0.920 mmol) and 0.28 mL of (R)-1-methyl-3,3-diphenylhexahydropyrrolo[1,2-c][1,3,2]oxazaborole (77 mg, 0.28 mmol) in toluene (10 mL) at −60° C. and allowed to warm to −15° C. before being placed in the freezer overnight. The reaction was quenched with 1M Na2CO3 (5 mL), diluted with EtOAc, and stirred for 20 min. The organic layer was washed with brine and dried (MgSO4). The crude product was charged (DCM) to a 40 g ISCO silica gel cartridge and gradient elution (5-60% EtOAc/hexanes) using an Isolera chromatography station gave (S)-isopropyl 2-(5-bromo-4-(3,3-difluoroazetidin-1-yl)-2,6-dimethylpyridin-3-yl)-2-hydroxyacetate 186 mg (51%). 1H NMR (500 MHz, DMSO-d6) δ 5.24 (s, 1H), 4.97-4.94 (m, 1H), 4.74-4.71 (m, 2H), 4.54-4.51 (m, 2H), 2.50 (s, 3H), 2.33 (s, 3H), 1.19 (d, J=5.9 Hz, 3H), 1.13 (d, J=5.9 Hz, 3H). LCMS (M+H)=395.1.

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