Synthesis of [3]Rotaxanes by the Combination of Copper-Mediated Coupling Reaction and Metal-Template Approach

Abstract

[3]Rotaxanes with two axle components and one ring component were synthesized by the combination of a coupling reaction using a transition-metal catalyst and a metal-template approach. Thus, [2]rotaxanes were prepared by the oxidative dimerization of alkyne promoted by macrocyclic phenanthroline-CuI complexes. The [2]rotaxane was reacted with a Cu(I) salt and an acyclic ligand to generate a tetrahedral Cu(I) complex. Metal-free [3]rotaxane was isolated by the end-capping reaction of the acyclic ligand, followed by the removal of Cu(I) ion. The stability of the tetrahedral Cu(I) complexes depended on the size of both the ring component and the acyclic ligand, which was correlated with the yield of the corresponding [3]rotaxane.

Complex lasso: new entangled motifs in proteins

“…On the other hand, there is no exact analogs of the L 2 , L 3 , L 6 , LS and LL lasso types. Most similar, doubly-threaded [3]rotaxane are still the exotics of chemical topology3839404142 with only one, recent example of triply-threaded [4]rotaxane known to us43. Properties and use of such compounds are still poorly understood, and hard to correlate with lasso proteins.…”

Stepwise, Protecting Group Free Synthesis of [4]Rotaxanes

“…These have included coordination bonds with a range of main group and transition row metal ions [ 26 , 27 , 28 ], anion-templation [ 29 , 30 , 31 , 32 ], π-stacking interactions [ 33 ], H-bonding [ 34 , 35 ] and radical-radical interactions [ 36 ], amongst others. However, the synthesis of more complex rotaxanes in which two or more macrocycles encircle a thread remains challenging [ 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 ].…”

Phenanthroline based rotaxanes: recent developments in syntheses and applications

“…In another advancement of this study, resorcinol-phen based macrocycles 11a,b were treated with bis(propargyl)phenanthroline moiety, 15 to result in stable tetrahedral Cu( i ) complexes, 16a,b ( Scheme 5 ). 10 The introduction of the blocking groups was achieved by the copper catalyzed azide–alkyne Huisgen cycloaddition (CuAAC) reaction with azide 17. The removal of copper ion by KCN delivered the required [2]rotaxanes 18a ( n = 6) and 18b ( n = 8) in 63 and 76% yields respectively.…”

“…In subsequent variations of this study, similar strategy was used to assemble many [3]rotaxane analogues with subtle variations in the end capping reaction using either azide–alkyne cycloaddition or Williamson ether synthesis. 21 …”