Catalytic "Active-Metal" Template Synthesis of [2]Rotaxanes, [3]Rotaxanes, and Molecular Shuttles, and Some Observations on the Mechanism of the Cu(I)-Catalyzed Azide-Alkyne 1,3-Cycloaddition
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- 作者：Vincent Aucagne ; José ; Berná ; James D. Crowley ; Stephen M. Goldup ; Kevin D. Hä ; nni ; David A. Leigh ; Paul J. Lusby ; Vicki E. Ronaldson ; Alexandra M. Z. Slawin ; Auré ; lien Viterisi
- 刊名：Journal of the American Chemical Society
- 出版年：2007
- 出版时间：October 3, 2007
- 年：2007
- 卷：129
- 期：39
- 页码：11950 - 11963
- 全文大小：726K
- 年卷期：v.129,no.39(October 3, 2007)
- ISSN：1520-5126
文摘
A synthetic approach to rotaxane architectures is described in which metal atoms catalyze covalentbond formation while simultaneously acting as the template for the assembly of the mechanically interlockedstructure. This "active-metal" template strategy is exemplified using the Huisgen-Meldal-Fokin Cu(I)-catalyzed 1,3-cycloaddition of azides with terminal alkynes (the CuAAC "click" reaction). Coordination ofCu(I) to an endotopic pyridine-containing macrocycle allows the alkyne and azide to bind to metal atomsin such a way that the metal-mediated bond-forming reaction takes place through the cavity of themacrocycle-or macrocycles-forming a rotaxane. A variety of mono- and bidentate macrocyclic ligandsare demonstrated to form [2]rotaxanes in this way, and by adding pyridine, the metal can turn over duringthe reaction, giving a catalytic active-metal template assembly process. Both the stoichiometric and catalyticversions of the reaction were also used to synthesize more complex two-station molecular shuttles. Thedynamics of the translocation of the macrocycle by ligand exchange in these two-station shuttles could becontrolled by coordination to different metal ions (rapid shuttling is observed with Cu(I), slow shuttling withPd(II)). Under active-metal template reaction conditions that feature a high macrocycle:copper ratio, [3]rotaxanes (two macrocycles on a thread containing a single triazole ring) are also produced during thereaction. The latter observation shows that under these conditions the mechanism of the Cu(I)-catalyzedterminal alkyne-azide cycloaddition involves a reactive intermediate that features at least two metal ions.