Diisopropylethylamine → tert-butyl 3-(1-methyl-4-nitro-1H-pyrazol-5-ylamino)propylcarbamate

Participants

Reaction Conditions

Reaction Steps

A mixture of 5-chloro-1-methyl-4-nitro-1H-pyrazole (0.81 g, 5 mmol), tert-butyl 3-aminopropylcarbamate (0.85 g, 4.88 mmol) and DIPEA (1.8 mL, 10.5 mmol) in EtOH (5 mL) was heated at 130° C. in the microwave for 90 min. On cooling the reaction mixture was concentrated under reduced pressure and the residue purified via silica gel column chromatography (0-100% EtOAc/isohexane) to afford tert-butyl 3-(1-methyl-4-nitro-1H-pyrazol-5-ylamino)propylcarbamate as a yellow gum (1.27 g, 85%). A mixture of this gum (0.3 g, 1 mmol), K2CO3 (0.41 g, 3 mmol) and methyl iodide (0.1 mL, 1.58 mmol) in DMF (5 mL) was stirred at 60° C. for 18 hr. More methyl iodide (0.1 mL, 1.58 mmol) was added and stirring at 60° C. was continued for 24 hr. The reaction mixture was cooled and concentrated under reduced pressure. The residue was triturated in DCM (100 mL), filtered and the filtrate concentrated under reduced pressure. Purification via silica gel column chromatography (0-100% EtOAc/isohexane) gave tert-butyl 3-(methyl(1-methyl-4-nitro-1H-pyrazol-5-yl)amino)propylcarbamate as a pale yellow gum (0.122 g, 38%). 1H-NMR (400 MHz, CDCl3) δ 8.03 (s, 1H), 4.60 (s, 1H), 3.77 (s, 3H), 3.20-3.14 (m, 4H), 2.86 (s, 3H), 1.72-1.61 (m, 2H), 1.42 (s, 9H).

Provenance & Evidence