Synthesis and Molecular Structures of Tetrasilyl Ethers of Calix[4]arenes

The tetrasilyl ethers calix[4]areneOSiMe(2)R (R = Me, H, vinyl, allyl) were prepared by salt elimination; the calix[4]arene was deprotonated with sodium hydride and subsequently reacted with chlorosilanes CISiMe2R. In general, DMF was chosen as solvent in order to steer the reactions in terms of a preference for the cone-conformation of the products. In the case of calix[4]areneOSiMe(3) both, partial-cone-and cone-conformers, were synthesised. All products were characterised by NMR H-1, C-13, Si-29) spectroscopy, mass spectrometry and single-crystal X-ray diffraction.