Rapid and Efficient Microwave‐Assisted Synthesis of N‐Carbamoyl‐L‐amino Acids

Abstract

A rapid and efficient method for the synthesis of N‐carbamoyl‐L‐amino acids is reported. The procedure, involving the reaction between urea and α‐amino acids sodium salts, was performed under microwave conditions using an unmodified domestic microwave oven. A careful study of the operative conditions indicated proline (1d) as the less reactive substrate and phenylglycine (1e) as the more reactive one among all the α‐amino acids tested. Substitution of urea with potassium cyanate produced a low conversion into the corresponding N‐carbamoyl derivative, and a possible explanation of this result is reported.

Keywords:

• amino acids
• N‐carbamoyl derivatives
• microwave
• potassium cyanate
• urea

Acknowledgment

Financial support was obtained from Ministero dell' Istruzione dell' Università e della Ricera (MIUR) Fondo Universitario per la Ricera Dipartimentale (FURD) 2004–2005 to G. V.). The authors are grateful to P. Martinuzzi for recording ¹H and ¹³C NMR spectra and P. Padovani for expert instrumental maintenance.