# General Synthesis of 2-Substituted Benzoxazoles Based on Tf2O-Promoted Electrophilic Activation of Tertiary Amides

## TL;DR

A new method is introduced for making 2-substituted benzoxazoles using triflic anhydride and 2-fluoropyridine, enabling versatile synthesis of various derivatives.

## Contribution

A novel Tf2O-promoted cascade reaction for synthesizing 2-substituted benzoxazoles from tertiary amides and 2-aminophenols.

## Key findings

- The method involves activation of amide carbonyl groups by Tf2O followed by nucleophilic addition and cyclization.
- The reaction is versatile, allowing synthesis of diverse benzoxazole derivatives by varying substrates.
- The cascade process includes intramolecular cyclization and elimination steps.

## Abstract

We report a method for the synthesis of 2-substituted benzoxazoles from tertiary amides and 2-aminophenols in the presence of triflic anhydride (Tf2O) and 2-Fluoropyridine (2-F-Pyr). The cascade reaction involves the activation of the amide carbonyl group by Tf2O, nucleophilic addition, intramolecular cyclization, and elimination. Furthermore, we explore the scope of this method by varying both the amide and 2-aminophenol substrates, highlighting its versatility in the synthesis of a wide range of functionalized benzoxazole derivatives.