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TCI Practical Example: Conversion of Carbonyl Group into Thiocarbonyl Group using Lawesson's Reagent

We are proud to present the conversion of carbonyl group to thiocarbonyl group using Lawesson's reagent.

Used Chemicals

• 2-Pyrrolidone [P0575]
• Lawesson's Reagent [B1133]
• Dichloromethane

Procedure

To a solution of Lawesson's reagent (2.38 g, 5.88 mmol) in dichloromethane (42 mL), 2-pyrrolidone (1.0 g, 11.75 mmol) in dichloromethane (42 mL) was added at room temperature under N₂ atmosphere. After stirring the reaction solution for 2 hours, the solvent was removed under reduced pressure and the residue was purified by column chromatography (hexane:ethyl acetate = 9:1 - 6:4), giving pyrrolidine-2-thione as a white solid (0.79 g, 66%).

Experimenter’s Comments

The reaction was carried out in the fume hood due to the bad smell of Lawesson’s reagent.
The reaction mixture was monitored by TLC (hexane:ethyl acetate = 3:2, Rf = 0.28).

Analytical Data

pyrrolidine-2-thione

¹H NMR (400 MHz, CDCl₃); δ 8.61 (brs, 1H), 3.61 (t, 2H, J = 8.0 Hz), 2.86 (t, 2H, J = 8.0 Hz), 2.20-2.12 (m, 2H).

¹³C NMR (101 MHz, CDCl₃); δ 205.83, 49.66, 43.21, 22.91.

Lead Reference

• Ruthenium Catalyzed Synthesis of Enaminones
• N. D. Koduri, H. Scott, B. Hileman, J. D. Cox, M. Coffin, L. Glicksberg, S. R. Hussaini, Org. Lett. 2012, 14, 440.