Ammonium Chloride → Ethyl 2-(2-Bromo-5-nitro-4-pyridyl)acetate

Participants

Reaction Conditions

Reaction Steps

2-Bromo-5-nitropyridine (1.84 g, 9.06 mmol) and trimethylsilanyl-acetic acid ethyl ester (1.53 g, 9.52 mmol) are dissolved under an atmosphere of argon in dry THF (10 ml). After cooling to −78° C., a solution of tetrabutylammonium fluoride (TBAF, 2.37 g, vacuum-dried overnight) in a mixture of THF and acetonitrile (10 ml/10 ml) is slowly added, so that the reaction temperature did not rise above −65° C. After complete addition, the mixture is stirred at −40° C. for 30 minutes, and at −20° C. for 10 minutes. The reaction mixture is re-cooled to −78° C., and 2,3-dichloro-5,6-dicyano-p-benzochinone (DDQ, 2.06 g, 9.06 mmol) is added. The suspension is allowed to warm to RT. TLC analysis indicated complete conversion. The reaction mixture is diluted with EtOAc and poured into a saturated solution of NH4Cl solution. The organic layer is separated, washed with brine, dried over Na2SO4, and the solvent is evaporated. The residue is purified by FCC (toluene/EtOAc 100:0 to 97:3) to afford the title compound. 1H NMR (CDCl3, 400 MHz): δ 1.26 (t, J=7 Hz, 3H), 4.01 (s, 2H), 4.19 (q, J=7 Hz, 2H), 7.53 (s, 1H), 9.06 (s, 1H). ES−−MS: 287, 289 [M−H]−.

Provenance & Evidence