Convenient Preparation of Primary Amides via Activation of Carboxylic Acids with Ethyl Chloroformate and Triethylamine under Mild Conditions

Primary amides were easily prepared in 22–99% yields from the corresponding carboxylic acids 1 or 5 with NH4Cl via activation with ClCO2Et and Et3N. The enantiomers of the corresponding primary amides of Cbz-, Boc-, or Fmoc-α-amino acids can be separated by using a chiral column.