Highly efficient enantioselective synthesis of 1,3-disubstituted 2,5-diketopiperazine derivatives via microwave irradiation

Abstract

Chiral 2,5-diketopiperazine (2,5-DKP) derivatives have a broad range of biological activities in the medicinal field. The synthetic protocols of 1,3-disubstituted 2,5-DKPs via base-catalyzed cyclization of chloroacetamide have been reported. However, there are several drawbacks, such as an overly long reaction time, low to moderate yield, and racemization of the products. The sequence modified herein of 1,3-disubstituted 2,5-DKPs involves microwave-assisted cyclization. It increases yields and reduces reaction time. Furthermore, employing N-PMB protection prevents racemization, which frequently occurs in the base-catalyzed cyclization reaction. Consequently, the rapid synthetic method of enantiomerically pure 1,3-disubstituted 2,5-DKPs via microwave reaction was established successfully.