2,2'-Bipyridine → 4-(benzyloxy)-6-chloro-3-cyclopropyl-3H-imidazo[4,5-c]pyridine

Participants

Reaction Conditions

Reaction Steps

In a separate flask 4-(benzyloxy)-6-chloro-3H-imidazo[4,5-c]pyridine 2.24 (502 mg, 1.93 mmol), cyclopropane boronic acid (334 mg, 3.89 mmol) and Na2CO3 (415 mg, 3.9 mmol) were taken up in 1,2-DCE (13 mL). The aforementioned catalyst mixture was then added to this mixture, washing with 4×1 mL 1,2-DCE. The resulting mixture was heated to 70° C. and was stirred open to the air. After 7 h, additional Na2CO3 (215 mg, 2.03 mmol) and boronic acid (170 mg, 2.0 mmol) were added along with a heated suspension of Cu(OAc)2 (182 mg, 1.0 mmol) and 2,2′-bipyridine (155 mg, 0.99 mmol) in 1,2-DCE (3 mL). After an additional 1.5 h, additional boronic acid (340 mg, 4.0 mmol) and Na2CO3 (415 mg, 3.9 mmol) were added and the reaction was capped and stirred overnight. After an additional 14.5 h, additional boronic acid (150 mg, 1.7 mmol) and Na2CO3 (215 mg, 2.03 mmol) were added and the mixture was stirred open to air. After an additional 1.5 h, the reaction mixture was cooled to r.t., was diluted with EtOAc (75 mL), and was filtered through Celite. The filtrate was washed with half-saturated aqueous NH4Cl (75 mL), water (50 mL), and brine (50 mL). The organic phase was dried over Na2SO4, filtered, and concentrated. Purification by silica gel chromatography (0% to 5% THF in DCM) provided 4-(benzyloxy)-6-chloro-3-cyclopropyl-3H-imidazo[4,5-c]pyridine 2.35.

Provenance & Evidence