Solvent-Free Conversion of Thioamides to Thioesters

Abstract

Diverse thioesters were efficiently prepared via the solvent-free reaction of thioamide derivatives with alkyl halides in the presence of catalytic amounts of 1,4-diazabicyclo[2.2.2]octane (DABCO) in small quantities of water and in good to excellent yields.

Keywords:

• Alkyl halides
• S-alkylation
• thioamides
• thioesters
• thiols

ACKNOWLEDGMENT

The University of Isfahan, which provided facilities for this research, is gratefully acknowledged.

Notes

^a Yields refer to isolated products.

^b Formation of some colored impurities was observed.

^a Thioamide derivative (1 mmol), alkyl halide (1 mmol), DABCO (0.05 mmol), temperature = 110 °C, time = 70 min.

^b All products were characterized by IR, ¹H NMR, ¹³C NMR, and elemental analysis.

^c All yields refer to pure isolated products.

^d Colorless to pale yellow liquids, which were crystallized very slowly (12–24 h), isolated by flash chromatography (silica gel, EtOAc–Hexane, 1:8).

^e An excess amount of CH₃I was added (2 mmol).