Microwave-Assisted Stereoselective One-Pot Synthesis of Symmetrical and Unsymmetrical 2,5-Diketopiperazines from Unprotected Amino Acids

The facile condensation of unprotected amino acids by a phosphite-promoted one-step coupling reaction is a highly efficient synthesis to generate stereoselective and optically pure symmetrical and unsymmetrical functionalized diketopiperazines. The use of microwaves enhanced by small amounts of ionic liquid is accompanied by significant improvement in reaction times and yields. Simple filtration through a pad of silica provides the pure compounds in very good to excellent yields. ( (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)