Solid-phase synthesis of biarylalanines via Suzuki cross-coupling and intramolecular N-acyliminium Pictet–Spengler reactions

Solid-supported masked peptide aldehydes containing 3- or 4-iodophenylalanine residues were subjected to Pd-catalyzed Suzuki cross-coupling reactions with arylboronic acids. The biarylalanines generated were applied in intramolecular N-acyliminium Pictet–Spengler reactions. In this way, a range of pharmacologically interesting aryl-substituted pyrroloisoquinolines was obtained in excellent purity (>95%).