Diastereoselective formation of cyclochiral amino acids-substituted resorcin[4]arenes

The Mannich reaction between selectively tetratosylated resorcin[4]arene, formaldehyde and (S)-phenylalanine (or (S)-phenylglycine) methylamide gave cyclochiral mono- or dibenzoxazines with high diastereoselection as revealed by NMR and X-ray structural studies. X-ray structures of the products show the variety of intramolecular interactions that can be responsible for the diastereoselection of this acid-catalyzed reaction.