Sequence-Selective Synthesis of Rotacatenane Isomers

Abstract

Rotacatenane is an interlocked compound composed of two mechanically interlocked macrocyclic components, i.e., a [2]catenane, and one axle component. In this paper we describe the selective synthesis of isomeric rotacatenanes. Two [2]rotaxanes with different phenanthroline moieties were synthesized by the oxidative coupling of an alkyne with a bulky blocking group, which proceeded in the cavity of the macrocyclic phenanthroline-Cu complex. The metal template method was used to install another cyclic component: the tetrahedral Cu(I) complex, which was composed of a [2]rotaxane and an acyclic phenanthroline derivative, was synthesized, and the cyclization of the phenanthroline derivative gave the rotacatenane. The sequential isomers of rotacatenanes were distinguished by (1)H and (13)C NMR spectroscopy.

Syntheses, Structures, and Spectroscopic Properties of 1,10‐Phenanthroline‐Based Macrocycles Threaded by PtC8Pt, PtC12Pt, and PtC16Pt Axles: Metal‐Capped Rotaxanes as Insulated Molecular Wires

“…In most of the preceding reactions, variable amounts of the unthreaded homocoupling product 2 were evident by TLC and NMR spectroscopy. In no case did yields improve when aqueous KCN was added as in Scheme or other studies …”

Mechanical Interlocking of Macrocycles in Different Sequences

“…More recently, in 2016, Saito and co-workers described the synthesis of a pair of [3]rotacatenane isomers with two macrocycles and one axle component that are interlocked in different orders. 8 Phenanthroline-derived macrocycles were first formed via an intramolecular alkyne coupling of 5 or 6. Cu + coordination to the phenanthroline then templated the formation of a new dumbbell inside the macrocyclic cavity upon a Cu + -catalyzed alkyne coupling of 7 to give the corresponding [2]rotaxanes.…”

Radial Hetero[5]catenanes: Peripheral Isomer Sequences of the Interlocked Macrocycles

“…[12] Apair of rotacatenane isomers,consisting of ad umbbell interlocked on the two sides of an unsymmetrical [2]catenane,has been recently prepared and characterized by Saito. [16] Despite the importance and high potential of exploiting sequence-specific properties that are due to mechanical interlocking,M IMs of other topologies that contain isomeric sequences of the interlocked macrocycles are yet to be realized.…”