3,4-dihydro-2H-pyran → 3-bromo-2-methyl-6-(1-(tetrahydro-2H-pyran-2-yl)-1H-1,2,4-triazol-3-yl)pyridine

Participants

Reaction Conditions

Reaction Steps

3-Bromo-2-methyl-6-(1H-1,2,4-triazol-3-yl)pyridine (0.7 g, 2.93 mmol) and 3,4-dihydro-2H-pyran (0.493 g, 5.86 mmol) were dissolved in tetrahydrofuran (20 mL). TFA (3.34 mg, 0.029 mmol) was added and the resulting solution was heated to 70° C. for 16 h. The reaction mixture was cooled to room temperature, diluted with ethyl acetate, filtered and poured into a separatory funnel containing water and ethyl acetate. The organic layer was concentrated under reduced pressure. Flash chromatography (0-60% ethyl acetate in hexane) gave the desired product as a white solid (0.40 g, 1.23 mmol, 42% yield). MS (ESI) m/z 325.1 [M+2]+. Alternate approach: 3-Bromo-2-methyl-6-(1H-1,2,4-triazol-3-yl)pyridine (1 equiv), 3,4-dihydro-2H-pyran (2 equiv) and methanesulfonic acid (0.08 equiv) were combined in tetrahydrofuran (8×vol). The solution was heated and stirred at 68° C. for 3.5 h then cooled to room temperature. Triethylamine (0.4 equiv) was added and the resulting solution was concentrated under reduced pressure to an oil. The oil was treated with acetonitrile and concentrated under reduced pressure iteratively until a solid was obtained. The solid was dissolved in acetonitrile and treated with water. The suspension was filtered and the solids were collected and dried. The crude product was slurried in hexanes, filtered and dried to give the purified title compound as a light pink solid.

Provenance & Evidence