tert-Butyl 2-(3-(2,5-Dimethyl-1H-pyrrol-1-yl)-5-(methoxy(methyl)carbamoyl)-1H-pyrazol-1-yl)ethylcarbamate → tert-Butyl 2-(5-Acetyl-3-(2,5-dimethyl-1H-pyrrol-1-yl)-1H-pyrazol-1-yl)ethylcarbamate

Participants

Reaction Steps

A 250-mL round-bottomed flask equipped with a magnetic stirrer was charged with 287d (7.82 g, 1.0 eq., 20.0 mmol) and THF (100 mL) under N2 protection. A solution of MeMgBr (3.0 M in ether) (17 mL, 2.5 eq., 50.0 mmol) was added at −78° C. The mixture was stirred at room temperature for 3 h and quenched with saturated NH4Cl solution. It was then concentrated under reduced pressure and the residue was extracted with ethyl acetate (3×50 mL). The combined organic layer was evaporated under reduced pressure. The residue was purified by silica-gel column chromatography eluting with 4:1 petroleum ether/ethyl acetate to afford 287e as colorless oil (5.40 g, 78%). MS-ESI: [M+H]+ 347.0. 1H NMR (500 MHz, CDCl3) δ 6.57 (s, 1H), 5.91 (s, 2H), 4.93 (bs, 1H), 4.71 (t, J=5.5 Hz, 2H), 3.62 (t, J=5.5 Hz, 2H), 2.57 (s, 3H), 2.16 (s, 6H), 1.28 (s, 9H).

Provenance & Evidence