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TCI Practical Example: TEMPO Oxidation Utilizing Iodobenzene Diacetate as a Reoxidant

We are proud to present the TEMPO-catalyzed oxidation of a benzyl alcohol derivative to a benzaldehyde derivative using iodobenzene diacetate.

Used Chemicals

• 1-Naphthalenemethanol [N0633]
• 2,2,6,6-Tetramethylpiperidine 1-Oxyl Free Radical (= TEMPO) [T1560]
• Iodobenzene Diacetate [I0330]
• Dichloromethane

Procedure

To a solution of 1-naphthalenemethanol (306 mg, 2.0 mmol) in dichloromethane (2 mL) was added TEMPO (31.2 mg, 0.20 mmol), iodobenzene diacetate (709 mg, 2.2 mmol) and the mixture was stirred at room temperature for 4 hours. Dichloromethane (12.5 mL)and saturated aqueous sodium thiosulfate solution (12.5 mL) were added and the mixture was stirred for 30 minutes to quench. Two layers were separated and the organic layer was washed with saturated aqueous sodium bicarbonate solution (10 mL), brine (10 mL), dried over sodium sulfate and filtered. The solvent was removed under reduced pressure and the residue was purified by column chromatography (ethyl acetate:hexane = 0:100 - 3:97 on silica gel) to give 1-naphthaldehyde as a yellow liquid (291 mg, 93% yield).

Experimenter’s Comments

The reaction mixture was monitored by TLC (ethyl acetate:hexane = 1:9, Rf = 0.50).

Analytical Data

1-Naphthaldehyde

¹H NMR (400 MHz, CDCl₃); δ 10.41 (s, 1H), 9.26 (d, J = 8.9 Hz, 1H), 8.11 (d, J = 8.4 Hz, 1H), 8.01 (d, J = 6.8 Hz, 1H), 7.93 (d, J = 8.9 Hz, 1H), 7.74-7.57 (m, 3H).

Lead Reference

• 2-(Hydroxyimino)aldehydes: Photo- and Physicochemical Properties of a Versatile Functional Group for Monomer Design
• • P. Gentili, M. Nardi, I. Antignano, P. Cambise, M. D’Abramo, F. D’Acunzo, A. Pinna, E. Ussia Chem. Eur. J. 2018, 54, 5410.