Synthesis of new Calix[4]arenes and Calix[4]naphthalenes via Sonogashira reactions, photochemically-induced reactions and [2+2] fragment condensation reactions

Al-Saraierh, Hassan (2007) Synthesis of new Calix[4]arenes and Calix[4]naphthalenes via Sonogashira reactions, photochemically-induced reactions and [2+2] fragment condensation reactions. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Calixarenes are macrocyclic compounds which can be produced with different sizes and functionalities. They are mainly synthesized by 'one-pot' base-induced condensation reactions of the corresponding phenol(s) with paraformaldehyde. For example, the most accessible and commonly-used calixarene, tetra-p-tert-butylcalix[4]arene is produced by such a reaction, of p-tertbutylphenol with para-formaldehyde. The well-defined "calix"- or "cup"-like shape in most of these compounds have made them attractive targets for host-guest and/or supramolecular studies and many other applications. -- The work described in this thesis concerns the synthesis and a study of the properties of some new modified calix[4]arenes and calix[4]naphthalenes which were synthesized using different methods. Among the topics dealt with are the following: (a) An attempt to develop a new methodology for the wide-rim modification of calix[4]naphthalene by using a suitably pre-functionalized precursor. (b) The synthesis of a new thiophene-based calix[4]arene using [2+2] fragment condensation reactions. (c) The synthesis of a new member of the homooxacalix[4]naphthalene family using [2+2] fragment condensation reactions. (d) The ability to modify the dimensions of the cavity of a calix[4]naphthalene by extending the bridging units with (-CH₂-CH₂-) and/or (-CH₂-O-CH₂-) groups. -- The narrow-rim hydroxyl groups of calixarenes are known to be resistant to substitution displacement. The Sonogashira coupling reaction with trimethylsilylacetylene and phenylacetylene, however, has now been extended to trimethylsilylacetylene and phenylacetylene, however, has now been extended to the bistriflate of p-tert-butylcalix[4]arene, previously known to be resistant to Stille, Neigishi, or Suzuki-Miyaura reactions. Under some of the reaction conditions investigated, the previously unknown narrow-rim mono- and diiodo-p-tert-butylcalix[4]arene products were also produced, in addition to the targeted narrow-rim mono- and dialkynyl products. Homocoupling of the narrow rim monoethynyl-p-tert-butyl-calix[4]arene produced a new narrow-rim rigid butadiyne-linked bis-p-tert-butylcalix[4 ]arene. -- Finally, the syntheses of several new donor-acceptor narrow-rim functionalized alkynylcalix[4]arenes, and their potential in nonlinear optical materials are described.

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