A molecular receptor selective for zwitterionic alanine

摘要: A molecular receptor has been synthesized joining an aza-crown ether with a chiral chromane which mimics the oxyanion hole of enzymes. With this apolar host–guest complex zwitterionic alanine achieved through formation up to seven H-bonds. This allows extraction aqueous chloroform phase, while other natural amino acids are poorly extracted or not at all. Due nature receptor, enantioselective from solution phase takes place. X-Ray analysis combined anisotropic effects, NOE and CD studies revealed absolute configuration both strong weak complexes. Modelling also support proposed structures. The presence oxyanion-hole motif in structure was corroborated by X-ray diffraction studies.