3,4-dihydro-2H-pyran → 4-Bromo-5-methyl-1-(tetrahydro-pyran-2-yl)-3-trifluoromethyl-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

To a solution of 4-bromo-5-methyl-3-trifluoromethyl-1H-pyrazole (1.4 g, 6.2 mmol, 1.0 equiv) in chloroform (31 ml) was added p-toluene sulphonic acid monohydrate (118 mg, 0.62 mmol, 0.1 equiv). The solution was cooled to 0° C. and 3,4-dihydro-2H-pyran (0.85 ml, 9.3 mmol, 1.5 equiv) was added drop-wise over 5 minutes. The mixture was allowed to warm to room temperature for 1 hour and the solvents were removed under reduced pressure. The crude mixture was purified by column chromatography (SiO2), eluting with 0→25% EtOAc-petrol over a linear gradient to afford the title compound 1.4 g (59%), LCMS (PS-A) Rt 3.72 min [M+H]+ 314.

Provenance & Evidence