Ultrasound-Assisted Synthesis of N-Acylcyanamides and N-Acyl-Substituted Imidazolones from Carboxylic Acids by Using Trichloroisocyanuric Acid/Triphenylphosphine

A convenient ultrasound-assisted one-pot synthesis of N-acylcyanamides starting from readily available carboxylic acids and sodium cyanamide has been developed. Upon activation in the presence of trichloroisocyanuric acid (TCCA) and triphenylphosphine, a range of carboxylic acids was converted into N-acylcyanamides in good to excellent yields within 10 minutes at room temperature without base. Remarkably, N-acyl-substituted imidazolones were readily accessible through guanylation-cyclization of the in situ generated N-acylcyanamides.