Using a convergent synthetic strategy, the synthesis of the previously elusive CVsymmetrical calix-[4]naphthalene from 1-naphthol is described. Using other independent convergent routes, syntheses of the other three isomeric calix[4]naphthalenes originally formed from the direct base-catalyzed condensation of formaldehyde with 1-naphthol are also described. All of these methods involved either a TiCl4or TFA-assisted coupling reaction to achieve the cyclization steps. A mechanism is proposed to account for the formation of the original three isomeric calix[4]naphthalenes from the base-catalyzed condensation of formaldehyde with 1-naphthol.

This Account is dedicated to Professor George Just (McGill University) and to the memory of the late Professors Guido Perold (University of the Witwatersrand) and Satoru Masamune (University of Alberta and M.I.T.) for giving me the initial opportunities to undertake research in chemistry under their guidance; and also to Janette, Melissa, Andreas, Noulla and Menelaos. SYNLETT 2005, No. 6, pp 0879-08910 6 . 0 4 . 2 0 0 5 Advanced online publication: 23.03.2005Abstract: The first naphthalene ring-based analogues of the betterknown and extensively studied calixarenes were synthesized in 1993. Since that time, our group has focused its research on the design and synthesis of other 'calixnaphthalenes'. These endeavours are motivated partly due to the synthetic challenges which they provide, and to the challenges in deciphering their structural and complexation properties. Calixnaphthalenes offer several advantages over their calixarene analogues. Among these are the facts that they can form deeper, more electron-rich and in some cases, chiral, cavities. They also provide a wide range of potential new scaffolds upon which to design and build new receptors for neutral, or charged guest species. Their supramolecular complexation properties have barely been explored as yet since in most cases, only relatively small quantities only of these compounds have been obtained. In this review, all of the known, and previously unreported calixnaphthalenes are described. As well, some of the compounds, which are described, are still subjects of ongoing research.

Calix[4]naphthalenes are a class of molecules which possess deeper cavities than those of the analogous calix[4]arenes. Preliminary data obtained for the complexation of [60]fullerene ("C 60 ") with the C 4 -symmetrical endo-calix[4]naphthalene 3 and its tert-butyl-substituted derivative 4 show that they form supramolecular 1 : 1 complexes with C 60 in benzene, toluene or CS 2 solution with relatively high association equilibrium constants (K assoc ). Reported herein are thermodynamic parameters and additional K assoc determined for the complexation of C 60 and calix[4]naphthalenes 3 and 4 which show that both a solvophobic effect and π-π interactions are major driving forces for the complexation process.

Calix[4]naphthalenes 11 and 12 in which hydroxyl groups are situated intraannularly can be oxidized with PTMATB and base to form the bis(spirodienone) 13, from 11, and bis(spirodienone) 20−21 and spirodienone 22, from 12. The prototype calix[4]naphthalenes 9 and 10 previously reported by us and which contain similar 1,5 dihydroxy functionalities extrannularly failed to afford the analogous spironaphthalenones. Model studies with the bis(1-hydroxy-2-naphthyl)methanes 8−8f provided support for the putative mechanism proposed for the formation of spirodienone calix[4]arenes and spironaphthalenones. The synthesis of the novel tert-butylcalix[4]naphthalenes 12 is described.

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