Bromide ion → 5-(3-Nitro-pyrazol-1-ylmethyl)-furan-2-carboxylic acid methyl ester

Participants

Reaction Steps

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a solution of 5-nitro-1H-pyrazole (10.95 g, 96.89 mmol) in dry acetone (219 mL) was treated with 5-chloromethyl-furan-2-carboxylic acid methyl ester (17.80 g, 96.89 mmol) followed by K2CO3 (67.61 g, 484.29 mmol) and TBA bromide (6.24 g, 19.37 mmol). The reaction mixture was stirred at rt overnight. Water (500 mL) was added followed by EA (1000 mL). The aq. layer was extracted with EA (2×500 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure. Purification of the residue by FC (50:50 hept-EA) gave the title compound as a yellow oil. TLC: rf (50:50 hept-EA)=0.26. LC-MS-conditions 02: tR=0.84 min. 1H NMR (400 MHz, CDCl3) δ 3.90 (s, 3H), 5.44 (s, 2H), 6.58 (d, J=3.5 Hz, 1H), 6.93 (d, J=2.5 Hz, 1H), 7.15 (d, J=3.5 Hz, 1H), 7.60 (d, J=2.3 Hz, 1H).

Provenance & Evidence