Cyclotriveratrylene synthesis

Cyclotriveratrylene synthesis is a poorly understood process, as with many reactions between phenols and aldehydes, and yields are as variable as the methods to prepare them a review lists fifteen different conditions that give between 21 and 89% yield. Despite this the compounds are worth preparing as they have an interesting affinity for buckminsterfullerene, C6o, and are cited in papers and patents that describe methods to isolate pure C6o from a mixture of fullerenes [50], It transpires that the threefold symmetry of cyclotriveratrylene is complementary to the threefold axis of C6o and that the two form very stable complexes in toluene as shown in Fig. 1.12, which precipitate leaving other fullerenes in solution. If the precipitate is isolated and taken up in chloroform the complex dissociates leaving cyclotriveratrylene in solution and precipitates C6o- The purity of the C6o treated in this way is significantly enriched and can approach 100%. At the time of this discovery fullerene research was very much in its infancy, and the material available was of variable purity, making the purification technique an important milestone in the history of fullerene chemistry. 

The facile condensation reaction between formaldehyde and phenols or their derivatives provides a major route into rigid macrocycles used in supramolecular chemistry. Calixarenes, the best-known class of phenol-derived macrocycles, are prepared this way, as are spherands and their relatives. Cyclotriveratrylene, however, is an excellent exemplar of the molecular basket type of ligand and has been known for the best part of a century. The basic cyclotriveratrylene synthesis is shown in Figure 3.1. The original procedure by Mrs. Gertrude Maud Robinson [1] has since been refined by others and many variations are known [2,3]. 

The work of Hyatt on cyclotriveratrylene—derived octopus molecules contrasts with this. Of course, these species have the advantage of ligand directionality absent in the benzene-derived octopus molecules. Except for the shortest-armed of the species (i.e., n = 1), all of the complexing agents (i.e., n = 2—4) were capable of complexing alkali metal cations. Synthesis of these species was accomplished as indicated below in Eq. (7.7). These variations of the original octopus molecules were also shown to catalyze the reaction between benzyl chloride and potassium acetate in acetonitrile solution and to effect the Wittig reaction between benzaldehyde and benzyltriphenylphos-phonium chloride. 

Collet, A., Dutasta, J.-P., Lozach, B., and Canceill, J. Cyclotriveratrylenes and Cryptophanes Their Synthesis and Applications to Host-Guest Chemistry and to the Design of New Materials. 165, 103-129 (1993). 

Cyclotriveratrylenes and Cryptophanes Their Synthesis and Applications to Host-Guest Chemistry and to the Design of New Materials... 

Canceill, J., Collet, A., Gabard, J., Kotzybahibert, F., Lehn, J. M., Speleands -macropolycyclic receptor cages based on binding and shaping subunits - synthesis and properties of macrocycle-cyclotriveratrylene combinations. Helv. Chim. Acta... 

Cyclotriveratrylene was first prepared by Gertrude Robinson in 1915 (Scheme 7.2). Robinson was interested in following up earlier work on the synthesis of anthracene derivatives and concluded that her product (empirical formula, C7H10O2, was 2,3,6,7-tetramethoxy-9,10-dihydroanthracene (7.43), the dimer of the intermediate veratryl cation (7.42). During the 1950s, CTV was again reformulated erroneously as a hexamer (7.44) and it was not until 1963 that the onset of a variety of modern techniques established a trimeric formula. 

Ahmad, R., Hardie, M. J., Synthesis and structural studies of cyclotriveratrylene derivatives. Supramol. Chem. 2006, 18, 29-38. 

Figure 10 Regioselective one-step synthesis of topologically chiral trans-3,trans-3,trans-3 and e,e,e [60]fullerene-cyclotriveratrylene tris-adducts.

Molecular cavities have been intensively studied over the last decades by supramolecular chemists, since they can be used for molecular recognition, catalysis, or transport processes across membranes. Bowl-shaped molecules such as calixarenes (28), res-orcinarenes (29), or cyclotriveratrylene (CTV, 30) derivatives constitute useful building blocks for cavities since their shapes and sizes can be controlled by covalent synthesis to a remarkable degree (Figure 3.15). The inherent flexibility of calixarenes and resorcinarenes can be limited either by substitution or by bridging, respectively. 

Since the end of the seventies, interest in cyclotriveratrylene has moved towards the use of its cone shaped structure for applications in various fields, including investigations of the electronic transitions of the benzene chromophore via UV and CD spectroscopy, studies in the area of host-guest chemistry, synthesis of new types of liquid crystals, and searches for new three-dimensional organic charge-transfer materials. These works have been made possible because efficient synthetic... 

The paper is organized as follows. Sect. 2 describes the general principles and recent results for the synthesis of cyclotriveratrylenes Sect. 3 describes some applications of these compounds to host-guest chemistry. This latter section is devoted principally to the cryptophanes, and to host molecules containing one CTV unit that have recently been described. Sec. 4 presents some prospective work in the field of material sciences, i.e., ferroelectric liquid crystals and organic three-dimensional charge transfer salts. 

We focus here on the preparation of functionalized C3-cyclotriveratrylenes bearing two different substituents X and Y on the peripheral positions of the three benzene rings. The synthesis of such compounds is based on the reaction shown in Fig. 2,... 

Figure 20 Acid-catalyzed synthesis of cyclotriveratrylene (CTV) and cyclotetraveratrylene (CTTV).

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