Transition metal-templated synthesis of catenanes

Figure 2.22. Strategies for the transition metal-templated synthesis of catenanes. The metal (in) predisposes two fragments as open chelates (A) (strategy I) or as a macrocyclic chelate (E) and an open chelate (strategy II) in intermediates (B) and (F), respectively. Cyclization of these intermediate complexes with the chain fragments (C) provides the [2]-catenate complex (D).

Figure 26 Strategies for the transition metal-templated synthesis of catenanes. The metal...

Fig. 17 Two strategies for the transition metal-templated synthesis of a [2]catenane made with Zn and Au porphyrin-incorporating interlocked macrocycles. The thick lines represent chelating fragments, the black disk symbolises copper(I), the empty diamonds are Zn(II) porphyrins, and the hatched diamonds are Au(III) porphyrins...

Sauvage, J.-P. Dietrich-Buchecker, C. O. Chambron, J.-C. Transition metals as assembling and templating species synthesis of catenanes and molecular knots. In Comprehensive Supramolecular Chemistry, Sauvage, J.-P. Hosseini, M.W., Ed., Publisher Elsevier, Oxford, UK 1996 Vol. 2, p 43. 

Fig. 27. Principle of the template synthesis of a catenane. The U fragment is a metal-chelating ligand and the black dot is a transition-metal ion with a pseudo-tetrahedral coordination geometry...

In the early 1980s, a transition-metal template strategy for the synthesis of catenanes was developed in our laboratory.9 It is based on the ability of Cu(I) to entwine two diphenylphenanthroline molecules in such a way that the coordination geometry around the metal is tetrahedral. Thus catenanes... 

We have seen how elegantly transition metals can template the formation of knots, but what about Nature s favourite templating interaction, the hydrogen bond A remarkably efficient molecular trefoil knot synthesis based on this interaction was reported by Vogtle and co-workers, who made a knotane in 20% yield [39]. This amazing route (Fig. 11) was uncovered serendipitously during the synthesis of catenanes. The crystal structure of the compound was the definitive proof for the structure, because neither NMR nor mass spectrometry could tell it apart conclusively from the macrocycles that are also formed. 

SYNTHESIS OF INTERLOCKING RINGS USING TWO DIFFERENT TRANSITION METALS AS TEMPLATING AND CONNECTING CENTERS RuCu(20.4) -", RuZn(20.4), AND RuAg(20.4) CATENANES TEMPLATE SYNTHESIS OF A 5-COORDINATE ZINC(1I) CATENANE,... 

The use of transition metal cations as templates in self-assembly pre-dates their utilization in the synthesis of catenanes. They were employed by Curtis and Busch in their pioneering work on macrocycle synthesis, while Sargeson... 

This elegant synthesis has demonstrated the possibility of using a hydrogen bond-acceptor template to prepare template-free interlocked species (in a similar fashion to Sauvage s catenanes syntheses which make use of transition metals as templates). 

Considering the efficiency of the 3D-template effect induced by transition metals in the synthesis of [2]catenanes, we tried to generalize our eoneept for obtaining [3]catenanes. Still relying on the copper(I)/l,10-phenanthroline couple, we eould develop two different strategies. 

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