2-Naphthoic acid → 2-Naphthoyl chloride

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In a flame dried rbf charged with nitrogen, a mixture of 2-naphthoic acid (0.516 g, 3 mmol), anhydrous m-xylene (14.83 mL) and thionyl chloride (11 mL) were refluxed for 2 hours. Rf=TLC (SiO2, 5% EtOAc/CH2Cl2) showed reaction was complete. The solvent was removed in vacuo resulting in 0.604 g of creamy white crystals of 2-naphthoyl chloride (100% yield). Fresh anhydrous m-xylene (5 mL) was added to 2-naphthoyl chloride (0.416 g, 2 mmol) and allowed to stir for 5 minutes, then a mixture of 2-amino-3-hydroxy-benzoic acid methyl ester (0.334 g, 2 mmol), triethylamine (3 mL) were added. The mixture was allowed to stir at room temperature for 4 hours, then the reaction mixture was heated to reflux and allowed to stir at refluxed temperature for 12 hours. The cooled mixture diluted with 100 mL of EtOAc and transferred to a separatory funnel, washed with of 0.1 M HCl (1×50 mL), H2O (1×50 mL) saturated NaHCO3 (1×50 mL), H2O (1×50 mL), and saturated NaCl (1×50 mL), respectively. The product was dried over Na2SO4; solvent was removed under pressure and concentrated in vacuo. The resulting 0.578 g of reddish-brown product was placed in a flame-dried rbf under N2 (g), then anhydrous m-xylene (14.4 mL), and PPTS (0.904 g, 3.6 mmol) were added. The reaction mixture refluxed for 4 hours. The cooled mixture was diluted with 100 mL EtOAc and transferred to a separatory funnel, washed with saturated NaHCO3 (1×50 mL), H2O (4×50 mL), and saturated NaCl (1×50 mL), dried over Na2SO4; solvent was removed under pressure and concentrated in vacuo using a coldfinger. The mixture was purified using flash chromatography Yield: 0.173 g tan solid (28% yield, 4 steps). Rf=0.40 (SiO2, 3% EtOAc/CH2Cl2). 1H NMR (400 MHz, CDCl3) δ 4.09 (s, 3H), δ 7.44 (t, J=7.8, 1H), δ 7.58-7.60 (m, 2H), δ 7.82 (dd, J=9.2 Hz, 1 Hz, 2H), δ 7.90 (d, J=7.3 Hz, 1H), δ 7.98-8.06 (m, 3H), δ 8.41 (dd, J=8.7 Hz, 1.8 Hz, 1H), δ 8.89 (s, 1H).

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