One-pot Ester and Thioester Formation Mediated by Pentafluoropyridine (PFP)

Acyl fluorides are valuable synthetic intermediates, but in some cases they can be challenging to handle and difficult to isolate given their susceptibility to degradation. In addition, many reagents utilised to prepare acyl fluorides are incompatible with in situ generation strategies and require the acyl fluoride to be isolated before any further reaction can take place. The combination of these factors has meant that acyl fluorides are currently under investigated in nucleophilic substitution processes, and often only a limited substrate scope is tolerated where they have been used. Herein, we report that pentafluoropyridine can be utilised to generate acyl fluorides in situ under mild conditions, and that they can subsequently be used to generate a range of esters and thioesters. This methodology offers a simple one-pot synthesis of esters and thioesters directly from parent carboxylic acids.