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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

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
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
A synthetic approach to rotaxane architectures is described in which metal atoms catalyze covalent bond formation while simultaneously acting as the template for the assembly of the mechanically interlocked structure. 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 of Cu(I) to an endotopic pyridine-containing macrocycle allows the alkyne and azide to bind to metal atoms in such a way that the metal-mediated bond-forming reaction takes place through the cavity of the macrocycleor macrocyclesforming a rotaxane. A variety of mono- and bidentate macrocyclic ligands are demonstrated to form [2]rotaxanes in this way, and by adding pyridine, the metal can turn over during the reaction, giving a catalytic active-metal template assembly process. Both the stoichiometric and catalytic versions of the reaction were also used to synthesize more complex two-station molecular shuttles. The dynamics of the translocation of the macrocycle by ligand exchange in these two-station shuttles could be controlled by coordination to different metal ions (rapid shuttling is observed with Cu(I), slow shuttling with Pd(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 the reaction. The latter observation shows that under these conditions the mechanism of the Cu(I)-catalyzed terminal alkyne?azide cycloaddition involves a reactive intermediate that features at least two metal ions
0002-7863
11950-11963
Aucagne, Vincent
898b235a-ef2f-4752-aaec-0f4d7cba6634
Berná, José
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Crowley, James D.
2d5e4e7f-b835-496a-a7db-e1a1856226db
Goldup, Stephen M.
0a93eedd-98bb-42c1-a963-e2815665e937
Hänni, Kevin D.
cebbe497-a98d-4b6b-8f26-0489cc7a94de
Leigh, David A.
826353b6-267f-44cd-a7e7-adf0c34f66c9
Lusby, Paul J.
7edd6163-af61-4425-83ef-bf48d9c9b094
Ronaldson, Vicki E.
d345332b-8a06-48a5-88c9-74d444686af7
Slawin, Alexandra M.Z.
45b99a30-c91c-4306-be37-6b7b0ec0affd
Viterisi, Aurélien
8a0854e8-d08b-488f-969d-1bb179101206
Walker, D. Barney
5a013019-0c8b-42c0-9eb0-78508c94777a
Aucagne, Vincent
898b235a-ef2f-4752-aaec-0f4d7cba6634
Berná, José
b5dcd6e7-4598-42ff-a3a2-728c4d49fc2d
Crowley, James D.
2d5e4e7f-b835-496a-a7db-e1a1856226db
Goldup, Stephen M.
0a93eedd-98bb-42c1-a963-e2815665e937
Hänni, Kevin D.
cebbe497-a98d-4b6b-8f26-0489cc7a94de
Leigh, David A.
826353b6-267f-44cd-a7e7-adf0c34f66c9
Lusby, Paul J.
7edd6163-af61-4425-83ef-bf48d9c9b094
Ronaldson, Vicki E.
d345332b-8a06-48a5-88c9-74d444686af7
Slawin, Alexandra M.Z.
45b99a30-c91c-4306-be37-6b7b0ec0affd
Viterisi, Aurélien
8a0854e8-d08b-488f-969d-1bb179101206
Walker, D. Barney
5a013019-0c8b-42c0-9eb0-78508c94777a

Aucagne, Vincent, Berná, José, Crowley, James D., Goldup, Stephen M., Hänni, Kevin D., Leigh, David A., Lusby, Paul J., Ronaldson, Vicki E., Slawin, Alexandra M.Z., Viterisi, Aurélien and Walker, D. Barney (2007) 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. Journal of the American Chemical Society, 129 (39), 11950-11963. (doi:10.1021/ja073513f).

Record type: Article

Abstract

A synthetic approach to rotaxane architectures is described in which metal atoms catalyze covalent bond formation while simultaneously acting as the template for the assembly of the mechanically interlocked structure. 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 of Cu(I) to an endotopic pyridine-containing macrocycle allows the alkyne and azide to bind to metal atoms in such a way that the metal-mediated bond-forming reaction takes place through the cavity of the macrocycleor macrocyclesforming a rotaxane. A variety of mono- and bidentate macrocyclic ligands are demonstrated to form [2]rotaxanes in this way, and by adding pyridine, the metal can turn over during the reaction, giving a catalytic active-metal template assembly process. Both the stoichiometric and catalytic versions of the reaction were also used to synthesize more complex two-station molecular shuttles. The dynamics of the translocation of the macrocycle by ligand exchange in these two-station shuttles could be controlled by coordination to different metal ions (rapid shuttling is observed with Cu(I), slow shuttling with Pd(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 the reaction. The latter observation shows that under these conditions the mechanism of the Cu(I)-catalyzed terminal alkyne?azide cycloaddition involves a reactive intermediate that features at least two metal ions

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Published date: 1 September 2007
Organisations: Organic Chemistry: Synthesis, Catalysis and Flow

Identifiers

Local EPrints ID: 370668
URI: https://eprints.soton.ac.uk/id/eprint/370668
ISSN: 0002-7863
PURE UUID: 1327d8f2-c7b4-4acb-a5af-67e4eafcab81
ORCID for Stephen M. Goldup: ORCID iD orcid.org/0000-0003-3781-0464

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Date deposited: 03 Nov 2014 13:49
Last modified: 15 Aug 2019 00:33

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