Rotaxanes statistical threading

Preparation of the first rotaxanes was also accomplished by means of statistical threading of a chain through a cycle with following attaching of bulky substituents to the loose ends of the threaded chain [5], Statistical means of molecular threading were pushed out by much more efficient covalent templation procedures developed by Schill etal. [6,7],... 

One of the earliest rotaxane syntheses was based on statistical threading (Figure 2.6).3 Harrison and Harrison coupled the 30-membered macrocycle 1 bearing a pendent carboxylic group to a Merrifield s peptide resin, forming... 

The early syntheses of catenanes and rotaxanes were mainly based on statistical threading approaches or on directed methodologies involving chemical conversion [30]. To obtain a catenated molecule, one ring must be closed in the presence of a... 

The very first rotaxanes were, however, not prepared via the template technique. In 1967, Schill and Zollenkopf [3] described a directed rotaxane synthesis (i.e. by the use of temporary, cleverly disposed covalent bonds), which was traced from the first directed catenane synthesis developed by Schill and Luttringhaus in 1964 [32]. Quite simultaneously, Harrison and Harrison published the first rotaxane synthesis by statistical threading [4]. 

One of the earliest rotaxane syntheses involved statistical threading. Harrison and Harrison [4] coupled the 30-membered macrocycle (3) bearing a pendent carboxylic group to a Merrifield s peptide resin, forming the resin adduct (4) (Figure 7). Next, a column was charged with this modified resin and treated with a solution of decane-1, 10-diol (5) and triphenylmethyl chloride (6) in a mixture of pyridine, dimethylfor-mamide and toluene. The process was repeated 70 times. After washing the column,... 

Figure 8 Statistical threading (temperature-controlled slippage). Preparation of [2]-rotaxane (10) [38],...

The first mention of synthetic rotaxanes appeared in 1967 [11]. It was based on statistical threading of an immobilized cycle by decane-1,10-diol followed by capping using a trityl ether bulky oup. Another system using statistical threading 1 to rotaxanes in relatively high yield [12]. A directed synthesis was also reported in 1969 by Schill and Zollenkopf.[13]... 

The first rotaxanes were prepared by a statistical synthetic approach. The threading of a macrocycle around a linear chain is based purely on chance no specific... 

This threading and stoppering technique was used by Schill and coworkers for a very elegant synthesis of a hydrocarbon catenane [54, 55]. The intermediate rotaxane was prepared in gram scale amounts, exemplilying the preparative value of the statistical method. 

The first catenanes and rotaxanes were constructed by either statistical [2] or directed [3] synthetic approaches. The statistical method relies [2] on the formation of small quantities of a species in which a cyclic molecule is threaded by an acyclic molecule. After experiencing appropriate covalent bond formation, these threaded species are con-... 

Frisch, H.L. and Wasserman, E. (1961) Chemical topology, J. Am. Chem. Soc. 83, 3789-3794. Schill, G. (1971) Catenanes, rotaxanes and knots. Academic Press, New York. Walba, D.M. (1985) Topological stereochemistry. Tetrahedron 41, 3161-3212. Dietrich-Buchecker, C.O. and Sauvage, J.P. (1987) Interlocking of molecular threads From the statistical approach to the templated synthesis of catenands, Chem. Rev. 87, 795-810. Philp, D. and Stoddart, J.F. (1991) Self-assembly in organic synthesis, Synlett 445-458. 

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