Synthesis of N-isoindolinonyl peptides via Pd-catalyzed C(sp²)–H olefination–activation and their conformational studies

Isoindolinone is a constituent of several natural products that show a wide range of bioactivity, such as anticancer, antimicrobial, antiviral and anti-inflammatory properties. It would be interesting to explore the carbonyl group (H-bond acceptor) of isoindolinone and its structural and conformational changes. However, the synthesis of isoindolinone-comprising peptides in short steps is challenging. Herein, we have developed a synthetic methodology for introducing the isoindolinone residue to peptides via Pd-catalyzed C(sp²)–H activation/olefination, and demonstrated the conformational changes owing to the isoindolinone scaffold. Hence, isoindolinonyl peptides provide an avenue for the synthesis of novel foldamers and therapeutic agents.