Chiral Metallocalix[4]arenes: Resolution by Diastereomeric Tungsten(VI) Alkoxides

The chiral metallocalix[4]arene [W(L)Cl2] (L = 3,4-dimethylcalix[4]arene) was resolved by means of tungsten alkoxide complex prepn. The dichloride was reacted with (1S,2S)-trans-1,2-cyclohexanediol or (S,S)-(-)-hydrobenzoin to give the substituted complexes. The hydrobenzoin complex diastereomers were more easily sepd. than those of the cyclohexanediol complex and were converted back to the dichlorides or to the oxides [WO(L)] as pure enantiomers. The CD spectra of the thus prepd. [W(L)Cl2] complexes are mirror images, confirming that they are enantiomers. [on SciFinder(R)]