一锅法由醛合成硫酰胺

One-pot tandem reactions of a variety of aldehydes with aqueous ammonia, molecular iodine, and O,O-diethyl dithiophosphoric acid readily afford the corresponding primary thioamides. This is an inexpensive, practical, and metal-free way of accessing various thioamides from aldehydes in aqueous media. The pure products are obtained simply by filtration followed by successive washing with aqueous sodium thiosulfate and water.

Plausible mechanistic pathway for oxidative conversion of aldehydes to thioamides

General Procedure for the One-Pot Synthesis of Primary Thioamides 

A mixture of benzaldehyde 1 (1.5 mmol) and iodine (1.6 mmol) in ammonia water (10 mL of 28% solution) was stirred at room temperature for 30 min. The dark reaction mixture faded in color at the end of reaction. The excess of ammonia was removed by stirring at 90 °C, and the gas was trapped in water. Then, O,O-diethyl dithiophosphoric acid (2) (1.5 mmol) was added and the reaction mixture was stirred at 90 °C for 2–4 h . After completion of the reaction (monitored by TLC), the mixture was cooled to rt. The product thus precipitated was filtered, washed with aqueous sodium thiosulfate solution followed by water, and dried under reduced pressure to give pure primary thioamides 3 . 

Synthetic Communications 2014, 44, 408-416

标签： thioamide