Hydrophobic-pocket-enabled organocatalysis: New stereodirecting diphenylethylenediamine-isosteviol thioureas for accelerated michael addition under green aqueous conditions

Abstract

A chiral 1,2-diphenylethylenediamine (DPEN) unit was incorporated into an isosteviol-derived thiourea organocatalyst to facilitate the Michael addition of aldehydes to maleimides in an aqueous medium. Operating under neutral conditions, the newly developed isosteviol-DPEN thiourea catalyst demonstrates exceptional performance. It not only affords Michael addition products in high yields, with values reaching up to 98 %, but also exhibits remarkable enantioselectivities, which can go as high as 99 %. Importantly, this catalyst achieves dual stereoselective control of the reaction, ensuring the formation of products with precise stereochemical configurations.