Side chain selective binding of N-acetyl-α-amino acid carboxylates by a 2-(guanidiniocarbonyl)pyrrole receptor in aqueous solvents

2-(Guanidiniocarbonyl)pyrrole 1 binds N-acetyl-α-amino acid carboxylates in 40% H2O–DMSO with binding constants ranging from K = 360 to 1700 mol–1 depending on the structure of the amino acid side chain.