Benzaldehyde → 3-Amino-2-phenylpyridine

Participants

Reaction Steps

To 2-chloro-3-aminopyridine (1.06 g, 8.24 mmol) in toluene (25 mL) was added benzaldehyde (0.878 g, 8.27 mmol). The reaction mixture was stirred at reflux in a Dean-Stark apparatus until GC/MS analysis of the reaction mixture no longer showed starting material. The reaction mixture was cooled to room temperature and the toluene solution containing benzylidene-(2-chloro-pyridin-3-yl)-amine was added to a mixture of phenylboronic acid (1.30 g, 10.7 mmol), sodium carbonate (2.66 g, 25.1 mmol), and tetrakis(triphenylphosphine)palladium(0) (47 mg, 0.38mol %) in water (10 mL). The reaction mixture was heated to 100° C. for 30 minutes, cooled to room temperature and poured into 1N aqueous sodium hydroxide (10 mL). The aqueous layer was removed and the toluene layer was extracted with 1N aqueous hydrochloric acid (twice with 15 mL). The aqueous layer was neutralized to pH 12 with 6N aqueous sodium hydroxide and extracted with MTBE (twice with 20 mL). The MTBE extracts were dried over magnesium sulfate, filtered and concentrated to afford 2-phenyl-3-aminopyridine as a solid which crystallized from diisopropyl ether (1.26 g, 90% yield). M. p.=87-68° C. 1H NMR (300 MHz, CDCl3) δ3.88 (bs, 2), 7.02-7.11 (m, 2), 7.28-7.53 (m, 3), 7.6714 7.71 (m, 2), 8.13-8.16 (m, 1). 13C NMR (100 MHz, CDCl3) δ122.57, 122.96, 128.14, 128.38, 128.72, 138.54, 139.86, 139.93, 144.93.

Provenance & Evidence