Although there have been a lot of reports on the synthesis and properties of [n]rotaxanes (mainly n = 2), only a few reports on the synthesis of [1]rotaxane has been published by Vogtle's group and others (see ref 5). Generally speaking, [1]rotaxane might be expected to exhibit properties different from other rotaxanes, because the rotor and the axle in the [1]rotaxane is bound covalently and closely. We report on a novel method to make [1]rotaxanes via covalent bond formation from a macrocyclic compound. That is, we first prepared a bicyclic compound from macrocycle and then proceeded to [1]rotaxane by aminolysis. This is the first synthetic example of preparation of [1]rotaxane via covalent bond formation, not utilizing weak interactions such as hydrogen bonding, charge transfer, via metal complexation, etc. This method might provide a powerful and new tool for construction of [1]rotaxane as a new supramolecular system. In addition, we investigated energy transfer from rotor to axle using [1]rotaxane that we prepared. Energy transfer occurred perfectly from the naphthalene ring of the rotor to the anthracene ring of the axle. We found also that only lithium ion among alkali ions can drastically enhance the fluorescence intensity. This finding could be applicable to ion-sensing systems, switching devices, and so on.

Synthesis of [1]rotaxane via covalent bond formation and its unique fluorescent response by energy transfer in the presence of lithium ion.

The tandem Claisen rearrangement is a simple but highly efficient reaction to synthesize useful building blocks for supramolecular chemistry. It provides in one step two new C–C bonds in very high yield. The scope and limits of this reaction will be discussed in this review and it will be shown, how macrocyclic compounds as well as rotaxanes or helicates can be formed by use of butenylidene bridged aromatic compounds obtained after the rearrangement reaction. Special aspects will cover the search for new receptors and sensors or for energy transfer properties. The contents of this tutorial review are within the field of preparative organic synthesis but in addition cover aspects of inorganic and supramolecular chemistry.

The tandem Claisen rearrangement in the construction of building blocks for supramolecular chemistry

Bis-calix[n]arenes that are singly and doubly bridged at the upper rims with 2-butenyl or 2-methylenepropyl moieties have been prepared by tandem Claisen rearrangement of bis-calix[n]arenes that are singly and doubly bridged via ether linkages at the lower rims with these same spanners. The complexation behavior of these bis-calixarenes toward C60 and C70 has been measured, and a calix[5]arene singly bridged at the upper rims with a 2-butenyl spanner and carrying allyl groups at all of the other available p-positions has been found to be particularly effective.

Complexation of Fullerenes with Bis-calix[n]arenes Synthesized by Tandem Claisen Rearrangement1

A novel synthesis of chiral rotaxanes via covalent bond formation

[3]Rotaxane synthesized via covalent bond formation can recognize cations forming a sandwich structure

Synthesis of novel crownophanes containing two phenolic moieties via a tandem claisen rearrangement

A series of crownophanes containing two phenolic moieties within a macrocyclic ring have been successfully synthesized by a one-step thermal reaction from the corresponding macrocyclic polyethers by using a “Tandem Claisen Rearrangement”.

Hide Kambayashi

Papers

Synthesis of novel crownophanes containing two phenolic moieties via a tandem claisen rearrangement

Synthesis of Novel Crownophanes Containing Two Phenolic Moieties via a Tandem Claisen Rearrangement.