Triptycenes, synthesis

Encapsulation of squaraine 23a in diastereomeric triptycene-based tetralactam macrocycles 24a and 24b was described in [61], The synthesis of the macrocyclic hosts was done by the reaction of pyridine-2,6-dicarbonyl dichloride and 2,7-diaminotriptycene in dry THF with Et3N. Macrocycles 24a and 24b readily form... 

Xue M, Chen CF (2008) Triptycene-based tetralactam macrocycles synthesis, structure and complexation with squaraine. Chem Commun 46 6128-6130... 

Triptycene has been prepared by Bartlett and co-workers 2 in a seven-step synthesis. 

The synthesis of the triptycene system illustrates a synthetic use of the important reactive intermediate benzyne (13) which is generated by the thermal decomposition of benzenediazonium-2-carboxylate (see Section 6.5.3, p. 900). The latter is produced when anthranilic acid (11) is treated with an alkyl nitrite in an aprotic solvent, and probably exists mainly as the zwitterionic form (12). 

Hart et al P7,78 also reported the preparation of symmetric iptycenes possessing benzene cores, for example, nonadecaiptycene (50) via bicyclic vinyl halide trimerization of triptycene dimer 51, as well as the synthesis of the related asymmetric iptycenes178 (Scheme 4.16). 

Wittig s classic synthesis of triptycene presumably involved 2-fluorophenylmagnesium bromide as an intermediate [1] ... 

The 1,6-, or bridgehead, carbon atoms in the beautifully symmetric molecule (I) can theoretically be substituted with any elements capable of (roughly) tetrahedral coordination, the most likely candidates being in Groups III, IV, V, and VI of the periodic table (see Fig. 1). The problem of their study is almost entirely one of synthesis, not stability. Although the first member of the series, 1,6-diazatriptycene (II), was apparently synthesized more than 100 years ago, (J) progress has been slow because only the 1,-6-diarsatriptycene skeleton can be built up in a stepwise fashion from stable intermediates (2). Special techniques must be devised for the other triptycenes and thus far, with one exception, only Group V derivatives have been synthesized. 

The simple method of direct synthesis in a heated, sealed tube is applicable to the more thermally stable triptycenes ... 

Before the chemistry of the 1,6-disubstituted triptycenes can be developed much further, a -good, general method is required for their synthesis. One possible route to the Group V triptycenes which has not been explored is to treat alkali or alkaline earth pnictides with aryl halides ... 

Using the triptycene-based homotritopic host 32, Chen et al. observed the tris[2] pseudorotaxane with 15 using ESI-MS <2005JA13158>. After metathesis, MALDI-TOF (TOE = time of flight) MS, X-ray crystallography (summarized in Section 14.22.3.1), and H and NMR were used in concert to prove synthesis of the [4]catenane. 

In Chapter 48 diphenyliodonium-o-carboxylate is utilized as a benzyne precursor in the synthesis of 1,2,3,4-tetraphenylnaphthalene. For reasons unknown, the reaction of anthracene with benzyne generated in this way proceeds very poorly and gives only a trace of triptycene. What about the... 

Based on our hypothesis that the acetylene was too flexible for 15/16 to function as a brake, we redesigned the system by deleting the acetylenic unit and connecting the pyridine directly to the triptycene as in 22. Unfortunately, the synthesis of 22 proved unsuccessful, because the reaction of the anthracene of 23 with benzyne then failed (Scheme 4). 

The synthesis of 47 and 48 is more difficult than the synthesis of the nonfunctionalized system 37b, in part because the lack of symmetry in the triptycene leads to a mixture of three interconvertible rotamers that must be isolated and identified. Nevertheless, the synthetic strategy developed is heavily based on the previous synthesis (see Sect. 6) of 37b. As summarized retrosynthetically in Scheme 10, the key steps for the synthesis of 47 and 48 are the preparation and photocyclization of the stilbene 54 containing the triptycene unit. Stilbene 54 would be formed by a Wittig reaction between aldehyde 55 and the ylide 56. Photocyclization and cleavage of the methyl ether would give phenol 53 which should allow the incorporation of tethers of variable length to give 47 or 48. 

Photoelimination of N2 from 3//-pyrazoles gives intermediate vinylcarbenes this reaction may have valuable applications in synthesis (Franck-Neumann et al.). Photochemists suffering from anosmia may be interested in the synthesis of 1,3-selenaphospholes described by Burkhart et al. Maier and Fleischer have reported a new photochemical route to tetra-t-butyltetrahedrane. McCarthy et al. have described the photochemical formation of triptycene from compound (47) the reaction is remarkable in involving the loss of one carbon atom, and the mechanism remains obscure. 

The stepwise synthesis of the perfluorinated 1,6-diphospha-, diarsa-, distiba- and dibisma-triptycenes (160), starting from 1,2-dibromotetrafluorobenzene via the dilithio-compounds, has also been described (Scheme 27) <85JOM(287)57>. 

Gong F, Mao H, Zhang Y, Zhang S, Xing W. Synthesis of highly sulfonated poly(arylene ether sulfone)s with sulfonated triptycene pendants for proton exchange membranes. Polymer 2011 52(8) 1738-47. 

The high reactivity of benzynes as dienophiles in Diels-Alder reactions has also been observed in reactions with aromatic hydrocarbons, a class of compounds usually considered as inert as dienes. In a two-step synthesis of triptycene di- and tetracarboxylic acids, arynes generated in situ from anthranUic adds 158 cydized with anthracenes 159 affording di- or tetramethyltriptycenes 160 in 41-69% yields (Scheme 12.47) [85], Acids 161 were obtained after subsequent oxidation of the cycloadducts 160 with potassium permanganate. 

Hu, S.-Z. and Chen, C.-F. Triptycene-derived oxacalixarene with expanded cavity Synthesis, structure and its complexation with fullerenes C50 and C70. Chem. Commun. 46, 4199 201, 2010. 

In this chapter, we will summarize our advances in studies on the synthesis, structures, molecular recognition and assembly of triptycene-derived calixarenes, heteracalixarenes and analogues. 

Scheme 18.3 Synthesis of triptycene-derived azacalixarenes 19-22 via a two-step method.

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