Auxiliary linkage

Metal and Auxiliary Linkage Approaches to Catenanes and Rotaxanes... 

Figure 10.64 The auxiliary linkage approach to the synthesis of [2] and [3] catenanes. The auxiliary linkage may be a covalent, coordinate or noncovalent bond.

Scheme 10.20 Directed synthesis of a [2] catenane by use of a negative templating steric barrier as an auxiliary linkage.71...

In addition to metal centres and covalent approaches, anions such as Cl may also be used as templating auxiliary linkages.80 Paul Beer and co-workers from the University of Oxford, UK, recognised that ion pairing in non-polar solvents such as acetone allowed the coordination of a neutral hydrogen bond donor such as 10.110 to the pyridinium salt 10.109, with a binding constant... 

Scheme 10.23 Strong ion-pairing in the pyridinium salt in non polar solvents allows the coordination of a neutral hydrogen bond donor and hence the creation of the precursor to a crossover in a catenane using the chloride ion as an auxiliary linkage.80...

Scheme 10.27 (a) Schematic diagram of the synthesis of a [2] catenane via the auxiliary linkage... 

Following on from the preparation of [2]catenate 10.103 (Scheme 10.27a), Sauvage realised that replacing the single Cu(l) core in [Cu(10.102)2] with a bimetallic double helicate would result in a precursor that, if it was stable enough to be cyclised, would immediately give a trefoil knot via a double auxiliary linkage approach (Scheme 10.27b). 

Scheme 10.27 (a) Schematic diagram of the synthesis of a [2] catenane via the auxiliary linkage approach, (b) Extension of this approach to the formation of a trefoil knot via a bimetallic double helicate. ... 

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