Amide-Based Catenanes

The sulfonamide macrocycle proved to be a hospitable template, and at the same time the sulfonamide functionality bears the possibility of farther derivatiza-tion of [2]rotaxanes (see Section 8.4 Chemistry with Amide-Based Catenanes and Rotaxanes). Furthermore the expansion of the cavity did not afford a change of the blocking group - no disassembly of wheel and axle was detected. 

Chemistry with Amide-Based Catenanes and Rotaxanes... 

The nonionic template strategy based on hydrogen bonds and to a certain extent on n-n interactions has made catenanes and rotaxanes readily available. The molecular recognition and self-organization process which is responsible for the formation of intertwined and interlocked structures is founded upon the same weak interactions that govern many biological processes. Amide-based catenanes and rotaxanes can thus serve as valuable models for complex molecular recognition patterns in nature. 

Scheme 10.18 Accidental synthesis of an amide-based [2] catenane.70...

Figure 2. Amide-based catenanes prepared by Hunter (catenane 3), Vogtle et al. (catenane 4), and Leigh et al. (catenane 5).

The functionalisation also allows extending the complexity of intertwined molecular assemblies involving molecular catenanes, rotaxanes and knots. Elaborate interlocked assemblies constructed by means of metal-templation techniques and ji-ji-stacking preorganisation were reviewed [3, 11], Our last survey was devoted to the hydrogen bond templated synthesis of amide-based catenanes and rotaxanes [32], Since then a considerable advancement in elucidation of mechanisms of templation and derivatisation of the amide-based interlocked structures has been reached. Moreover, in 2000 we reported a one pot synthesis of amide-based knots such as 8 [21], which is so far the easiest preparation of molecular knots. In the following, specific possibilities of functionalisation of amide-based catenanes, rotaxanes and knots will be discussed. 

Template Synthesis of Amide-based Catenanes, Rotaxanes and Knots... 

Figure 4. Hydrogen bond templated threading of a tetraamide ring in synthesis of amide-based catenanes and...

In the introduction we mentioned extravagant interlocked structures of higher complexity such as doubly intertwined catenane and molecular composite knots of Sauvage et al. and multicatenanes made up of 4 to 7 interlocked rings obtained by Stoddart et al. In this section, we will discuss assemblies made up of amide-based catenanes, rotaxanes and knots. Here we use the term assembly to describe covalent or... 

Heim, C., Udelhofen, D., Vogtle, F. Amide-Based Catenanes, Rotaxanes and Pretzelanes in J.-P. Sauvage, C. Dietrich-Buchecker (eds.), Molecular Catenanes, Rotaxanes and Knots. A Journey Through the World of Molecular Topology, Wiley-VCH, 1999, pp. 177-222. 

The amide-based template synthesis of rotaxanes, catenanes and knots were first discovered by Vogtle and coworkers when they tried to synthesize macrocycle 3 [13], The cyclization to yield the tetralactam ring was carried out under high-dilution... 

New catenane (cf. 17) and rotaxane (cf. 20) types have been obtained via supramolecular template syntheses The amide-based interlocked structures can be designed by appropriate choice of building units (cf. 13, 14) to form stable out/out, in/in and in/out isomers (cf. 17a, 17b), which can be separated [19]. It can be demonstrated that one of the two macromonocycles (cf. 15) of the... 

Scheme 3. Template synthesis by Vogtie and co-workers of amide-based catenanes with a concave template The catenation of the macromonocycle 15 with 13a and 14 leads to formation of catenane 17. The guest diacid dichloride 13a and the host 15 are locked in an orthogonal arrangement 16. The functional groups are fixed and thus preorganized for reaction with the diamine 14.

Physical properties of these poly[2] catenaries have been explored in expectation of unique properties based on the catenane structure [239, 246]. While various interesting physical properties were found in polyrotaxane, no characteristic property has been reported in [2]catenanes so far. Although poly[2]catenane has highly mobile moiety due to the mechanical bond, it has been suggested that the connection between [2]catenane subunit restricted the mobility in motion of [2]catenane. Further, intramolecular interaction in [2]catenane subunit may decrease its mobility. Secondary amide-based [2]catenanes can easily be prepared from commercially available compounds. Takata et al. found that the borane-reduction of the [2]catenanes afforded good yields of the amine-based [2]catenanes that can be useful for polymer synthesis [247, 148] (Scheme 51). Although the origi-... 

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