Base-Assisted Intramolecular C-N Coupling Reaction from NH2-Bound Cyclopalladated L-Phenylalanine to Indoline-2-carboxylic Acid

The deprotonative intramolecular-amination reaction of phenylalanine-derived palladacycles has been investigated to highlight a facile carbonate-assisted N-H activation before the C-N bond formation. A major counterion effect led to divergent pathways whereby the SPhos-Pd complexes with iodine, triflate, or trifluoroacetate anions were key intermediates to afford access to (S)-2-indolinecarboxylic acid derivatives.