Hydrogen bonding amide based synthesis

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. 

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

Ranganathan, D. Haridas, V. Sundari. C.S. Balasubra-manian, D. Madhusudanan. K.P. Roy. R. Karle, I.L. Design, synthesis, crystal stmcture, and host-guest properties of polymethylene-bridged cystine-based cyclobis-amides A facile entry to hydrogen-bonded peptide nanotubes. J. Org. Chem. 1999, 64 (25), 9230-9240. 

The first amide-based oligo[2]catenanes were successfully prepared, via route 2 in Scheme 17.3, by Geerts etol. in 1995 (see Scheme 17.4) [62]. Here, the first stage of the synthesis involved the creation of a dibromide-functionalized [2]catenane, via Hunter s two-step strategy, such that two isomers - IN-OUT 6a and OUT-OUT 6b -were obtained in 5% and 9% yields, respectively. However, due to the inter-molecular hydrogen bonding, the isomeric catenanes were conformationally frozen and could not be interconverted, even at relatively high temperature [60-63]. A... 

Jprgensen s group has very recaitly d onstrated the usefulness of o,P-unsaturated acyl phosphonates as hydrogen-bond acceptors in the enantioselective Hiedel-Crafts reaction with indoles [341]. Since the acyl phosphonate moiety is a powerful ester and amide surrogate, this reaction is an interesting approach towards the synthesis of optically active p-(3-indolyl)esters and amides as represented in Scheme 2.119 for selected examples. The reaction is catalyzed by chiral thiourea-based catalyst ent-191 that activates the nucleophile and the electrophile through hydrogen-bond interactions. 

Finally, in order to find a way of fine-tuning melting point and aqueous solubility of a representative. A, of a family of anticancer compounds, Aakeroy and coworkers reported the synthesis of five cocrystals with aliphatic, even-chained, dicarboxylic acids. The supramolecular synthesis was driven by the well-known COOH- py hydrogen-bond-based synthon, and in each reported case, infinite APT diacid- API- diacid chains were obtained, and these were subsequently arranged into 2D layers driven by API-based self-complementary amide- amide hydrogen bonds (Scheme 23). 

Synthesis of phosphoramidate-based hybrid compounds by using polyoxoanions may be valuable for spending the time on its consideration and experiment. Some of the well-known hybrids contain the molecule-cation components of the type [B—H...BJ+, where the B may be a base such as amide. Designing of such molecule-cation pairs with phosphoramidates, [PO—H...OP]+, may extend the experimental data about the 3ip 3ip coupling constant through the hydrogen-bond. 

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