Untersuchungen zur statistischen Synthese von Rotaxanen

Abstract

Die Rotaxane 6a-g und 9a-e werden nach der statistischen Methode synthetisiert. Die Ausbeuten, die von 0.35-6.8% bzw. 4.5-11.3% in Abhangigkeit von der RinggroDe bzw. Lange der Hantel ansteigen, wurden durch HPLC-Analyse bestimmt. Die Rotaxane 6f und 9a wurden isoliert. Die 'H-und "C-NMR-Spektren dieser Verbindungen und ihrer molekularen Untereinheiten werden diskutiert. Studies on the Statistical Synthesis of RotaxanesThe rotaxanes 6a-g and 9a-e are synthesized following statistical methods. The yields increasing from 0.35 to 6.8% and 4.5 to 11.3%, respectively, as a function of ring size and chain length of the dumpbell were determined by HPLC analysis. The 'H and ''C NMR spectra of these compounds and their molecular subunits are discussed.Wie Harrison gezeigt hat, lassen sich Rotaxane 3 nach der statistischen Methode aus einer langkettigen Verbindung mit sperrigen Endgruppen (Hantel) 1 und Ma- Die Gleichgewichtseinstellung zwischen 1,2 und 3 kann durch saurekatalysierte, reversible Abspaltung der sperrigen Endgruppen oder bei geeignetem Verhaltnis zwischen Raumerfiillung der Sperrgruppen und Durchmesser der Makrocyclen thermisch erreicht werden. Im Falle von 1 a wurden die Ausbeuten an Rotaxanen

Synthesizing interlocked molecules dynamically

“…Theoretically, it costs less energy for the half‐dumbell thread to find a larger hole. Using the trityl thioethers 1c or 1d instead of ethers (Scheme , third and fourth lines) produced similar results 21. In an interesting experiment, variation in the length of the dumbbell also produced different yields of [2]rotaxanes 3d .…”

“…The dynamic character of olefin metathesis has also been used to construct rotaxanes49 through a “magic” rod experiment. In this type of experiment, the ring component is covalently fixed, whereas the dumbbell contains a dynamic bond as in several previously discussed examples 18–22,25,30,31. Leigh and coworkers50 synthesized the symmetrical dumbbell 28 with a central double bond (Scheme ).…”

Templated Synthesis of Interlocked Molecules

“…Thus, Harrison postulated that, as a result of the acid-catalyzed reversible cleavage of the triaryl group, the species that threads through the C 25 -C 29 rings, is now only the monotriphenylmethyl ether (i.e., the half dumbbell) prior to reformation of the ether linkage. In 1986, Schill [144] reported a similar synthesis of interlocked molecular compounds obtained by the reversible covalent bond approach but using thioethers instead of ethers.…”

“…This approach has led to the preparation of rotaxanes by either threading-followedby-stoppering [152,[182][183][184] or slippage [135][136][137][138][139][140][141][142][143][144][145][146][147][148] protocols. However, in 2001, the Stoddart group [185] reported a simple and highly effective dynamic procedure (Scheme 10) for the formation of a [2]rotaxane by the clipping of a diamine with a dialdehyde, as the precursor components of a [24]crown-8-like macrocycle, around a dialkylammonium center that also acts as a template.…”

Carbon Nanostructures in Rotaxane Architectures

“…The synthesis of rotaxane derivatives including oligomeric and polymeric analogs, porphyrin‐stoppered rotaxanes,, cyclodextrin‐rotaxanes,, and rotaxane dendrimers, has also been reported in the literature through different methods. However, the incorporation of carbon nanostructures into the mechanically interlocked molecular architectures is not a straightforward task and a lot of effort has been dedicated to this goal .…”