Direct organocatalytic coupling of carboxylated piperazine-2,5-diones with indoles through conjugate addition of carbon nucleophiles to indolenine intermediates

Organocatalytic conjugate addition of diketopiperazines to indoles was achieved in good to excellent yields through electrophilic indolenine intermediates generated under mild conditions. Screening of catalysts and solvents at different temperatures was performed in order to achieve high product yields.