Cesium carbonate → 5-Chloro-6-[(1,3-dihydro-1-hydroxy-2,1-benzoxaborol-5-YL)oxy]-2-[(4-oxopentyl)oxy]-3-pyridinecarbonitrile

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Reaction Conditions

Reaction Steps

Into a 250-mL 3-necked round-bottom flask purged and maintained with an inert atmosphere of nitrogen were placed a solution of 5,6-dichloro-2-(4-oxopentyloxy)nicotinonitrile (1.12 g, 4.12 mmol, 1.00 equiv) in DMSO (50 mL), benzo[c][1,2]oxaborole-1,5(3H)-diol (650 mg, 4.33 mmol, 1.05 equiv) and Cs2CO3 (1.60 g, 4.92 mmol, 1.20 equiv). The resulting solution was stirred for 2 h at 40° C., then quenched by the addition of 100 mL of ice water. The resulting solution was extracted with 3×50 mL of ethyl acetate. The organic layers were combined, washed with 2×50 mL of water and 1×50 mL of brine, then dried over Na2SO4 and concentrated under vacuum. This resulted in 1.3 g (80%) of 5-chloro-6-(1-hydroxy-1,3-dihydrobenzo[c][1,2]oxaborol-5-yloxy)-2-(4-oxopentyloxy)nicotinonitrile as a white solid. LC-MS (ES, m/z): 387 [M+H] 1H-NMR (300 MHz, DMSO-d6) δ (ppm) 9.28 (1H, s), 8.60 (1H, s), 7.81 (1H, d, J=7.8 Hz), 7.33 (1H, s), 7.25 (1H, d, J=7.8 Hz), 5.02 (2H, s), 4.00 (2H, t), 2.35 (2H, t), 2.05 (3H, s), 1.8-1.6 (2H, m).

Provenance & Evidence