Synthesis of piperazinones and benzopiperazinones from 1,2-diamines and organoboronic acids

Alkenyl, aryl and heteroaryl boronic acids react with 1,2-diamines and glyoxylic acid to give directly in one step the corresponding piperazinones (2-oxopiperazines). Similarly, the use of monoprotected 1,2-phenylenediamine leads to benzopiperazinones (1,2,3,4-tetrahydroquinoxalin-2-ones).