Cesium carbonate → 4-(6-Nitropyridin-3-yl)-3-oxopiperazine-1-carboxylic acid tert-butyl ester

Participants

Reaction Conditions

Reaction Steps

A microwave vial was charged with 332a (1.5 g, 7.5 mmol) in 30 mL of anhydrous 1,4-dioxane, 5-bromo-2-nitropyridine (1.27 g, 6.25 mmol), diacetoxypalladium (71.8 mg, 0.32 mmol), Xantphos (278 mg, 0.48 mmol), and Cs2CO3 (2.04 g, 6.25 mmol). After three cycles of vacuum/argon flash, it was heated at 120° C. under microwave irradiation for 1.5 h. The reaction mixture was filtered and the filtrate was evaporated in vacuum. The residue was purified by silica gel-column chromatography eluting with 3:1 petroleum ether/ethyl acetate to afford 332b as a yellow solid (1.1 g, 54%). MS: [M+H]+ 323. 1H NMR (500 MHz, CDCl3) δ 8.68 (d, J=2.5 Hz, 1H), 8.31 (d, J=9 Hz, 1H), 8.15 (m, 1H), 4.33 (s, 2H), 3.91 (m, 4H).

Provenance & Evidence