Isobutyl Chloroformate

• 2-Chlorobenzoic acid [C0133]
• Furfurylamine [F0091]
• Isobutyl chloroformate [C0178]
• Triethylamine [T0424]
• Dichloromethane

To a 4-necked round-bottom flask was charged with 2-chlorobenzoic acid (1.0 g, 6.38 mmol, 1 eq.) and CH₂Cl₂ (25 mL) under nitrogen atmosphere. The flask was cooled to 0 °C in an ice bath. Et₃N (0.97 mL, 7.02 mmol, 1.1 eq.) was added dropwise and then isobutyl chloroformate (0.92 mL, 7.02 mmol, 1.1 eq.) was added dropwise at 0 °C. The mixture was stirred for 15 min, furfurylamine (0.71 mL, 7.66 mmol, 1.2 eq.) was added dropwise at 0 °C. The mixture was stirred at room temperature for 15 min and monitored by TLC. The reaction was quenched with water (5 mL). The organic layer was washed with 2 mol/L HCl (10 mL), saturated NaHCO₃ aq. (10 mL), and brine (10 mL), dried with Na₂SO₄ and then concentrated under reduced pressure. The crude product was purified by column chromatography on silica gel (hexane : ethyl acetate = 7 : 3) to afford the corresponding compound as white solid (1.45 g, 96%).

The reaction mixture was monitored by TLC (hexane / ethyl acetate = 2 : 1, Rf = 0.37).

¹H NMR (400 MHz, CDCl₃); δ 7.39 (d, J = 6.9 Hz, 2H), 7.29-7.42 (m, 4H), 6.52 (br s, 1H), 6.34 (d, J = 6.4 Hz, 2H), 4.67 (d, J = 5.5 Hz, 2H).

¹³C NMR (101 MHz, CDCl₃); δ 166.2, 150.7, 142.3, 134.6, 131.4, 130.7, 130.3 130.2, 127.1, 110.5, 107.7, 37.1.

• Practical Synthesis of Phenanthridinones by Palladium‐Catalyzed One‐Pot C–C and C–N Coupling Reaction: Extending the Substrate Scope to o‐Chlorobenzamides
  • H. Liu, W. Han, C. Li, Z. Ma, R. Li, X. Zheng, H. Fu, H. Chen, Eur. J. Org. Chem. 2016, 389.