2-Methylbenzenesulfonic acid → HCID 90461215, compound

Participants

Reaction Steps

A solution of ethyl 5-iodo-3-methyl-1H-pyrazole-4-carboxylate (2.1 g, 7.50 mmol, 1.00 equiv), 3,4-dihydro-2H-pyran (3.15 g, 37.45 mmol, 4.99 equiv) and toluenesulfonic acid (258 mg, 1.50 mmol, 0.20 equiv) in tetrahydrofuran (100 mL) was stirred at 80° C. for 8 h. The reaction mixture was cooled to room temperature and then diluted with H2O. The pH value of the solution was adjusted to 7 with saturated sodium bicarbonate solution. The resulting solution was extracted with 3×80 mL of ethyl acetate. The combined organic layers were washed with 1×80 mL of brine, dried over anhydrous sodium sulfate and concentrated under vacuum. The residue was purified on a silica gel column eluted with 0-25% of ethyl acetate in petroleum ether to give 1.5 g (55%) of (R/S) ethyl 5-iodo-3-methyl-1-(oxan-2-yl)-1H-pyrazole-4-carboxylate as a yellow oil. 1H-NMR (300 MHz, DMSO-d6): δ 5.45 (dd, J=9.9 Hz, 1H), 4.24 (q, J=7.2 Hz, 2H), 3.88-3.84 (m, 1H), 3.69-3.60 (m, 1H), 2.49 (s, 3H), 1.95-1.75 (m, 2H), 1.65-1.45 (m, 4H), 1.29 (t, J=7.2 Hz, 3H) ppm. LCMS (method D, ESI): RT=1.55 min, m/z=365.0 [M+H]+.

Provenance & Evidence