A Novel C3-Symmetric Triol as Chiral Receptor for Ammonium Ions

The enantiopure C3-symmetric syn-benzotriborneol was efficiently obtained in an eight-step route. Of particular interest from a synthetic point of view are the potassium tert-butoxide promoted bromination of camphor hydrazone (4) and the observation that the protecting groups influence the syn/anti diasteroselectivity of the cyclotrimerization reaction of 12–14. Complexation studies in deuteriochloroform revealed the capability of the cyclotrimer syn-1 to act as host for ammonium ions, and in particular, the efficient chiral recognition of the two enantiomers of (1-phenylethyl)ammonium chloride.