Highly Efficient One-Pot Synthesis of 2-Aminobenzoxazoles Using Triflic Acid as a Cyclodesulfurizing Reagent

Abstract

An efficient one-pot synthetic strategy for 2-aminobenzoxazoles was developed from isothiocyanates and 2-aminophenol using triflic acid as a cyclodesulfurizing reagent.

Keywords:

• 2-Aminobenzoxazole
• cyclodesulfurization
• one-pot synthesis
• triflic acid

ACKNOWLEDGMENT

We are thankful to the Department of Science and Technology, government of India, for the research funding.

Notes

^a The reaction was carried out by stirring a mixture of 4-chlorophenyl isothiocyanate (1.83 mmol, 1.0 equiv) and 2-aminophenol (1.83 mmol, 1.0 equiv) in THF (10 mL) for 0.5 h for intermediate thiourea formation followed by the addition of the reagent and refluxing for the time indicated.

^b The product was characterized by NMR and mass spectroscopic methods.

^a The reaction was carried out by stirring a mixture of 4-chlorophenyl isothiocyanate (1.83 mmol, 1.0 equiv) and 2-aminophenol (1.83 mmol, 1.0 equiv) in solvent (10 mL) for 2 h for intermediate thiourea formation followed by the addition of the triflic acid (2.2 mmol, 1.2 equiv) and refluxing for the time indicated.

^b The product was characterized by NMR and mass spectroscopic methods.

^a The reaction was carried out by stirring a mixture of isothiocyanate (1.83 mmol, 1.0 equiv) and 2-aminophenol (1.83 mmol, 1.0 equiv) in THF (10 mL) for 0.5 h for intermediate thiourea formation followed by the addition of the triflic acid (2.2 mmol, 1.2 equiv) and refluxing for the time indicated.

^b The product was characterized by NMR and mass spectroscopic methods.

^c The reaction mixture was refluxed for 1 h for intermediate thiourea formation followed by the addition of the triflic acid (2.2 mmol, 1.2 equiv) and refluxing for the time indicated.