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

Participants

Reaction Conditions

Reaction Steps

A solution of 4-bromo-5-methyl-3-(trifluoromethyl)-1H-pyrazole (1.00 g, 4.37 mmol) and p-toluenesulfonic acid monohydrate (80 mg, 0.4 mmol) in CHCl3 (3.5 mL) was cooled to 0° C. and dihydropyran (480 μL, 5.2 mmol) was added dropwise. The reaction was stirred at 0° C. for 1.5 h. The solvent was removed in vacuo and the residue was purified by column chromatography to obtain the desired product (1.18 g, 86%). 1H NMR (400 MHz, CDCl3): δ 5.35 (dd, 1H), 3.98 (m, 1H), 3.65 (m, 1H), 2.40 (m, 1H), 2.37 (s, 3H), 2.12 (m, 1H), 1.96 (m, 1H), 1.64 (m, 3H).

Provenance & Evidence