Selecting reactions and reactants using a switchable rotaxane organocatalyst with two different active sites

Beswick, Jack; Blanco, Víctor Francisco Sampedro; Bo, Guillaume De; Leigh, David A.; Lewandowska, Urszula; Lewandowski, Bartosz; Mishiro, Kenji

doi:10.1039/c4sc03279a

Cited by 134 publications

(68 citation statements)

References 83 publications

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“…In the case of the molecular shuttle, the easiest way to confer bistability is to incorporate two (very) different recognition sites onto the axle of the dumbbell component of a [ 2]rotaxane ( Figure 4b). [85] This objective can be achieved by replacingt he hydroquinone recognition sites in the moleculars huttle by tetrathiafulvalene and 1,5-dioxynaphthaleneu nits, [86] as strong and weakr ecognition sites, respectively,i nawide range of donor-acceptor rotaxanes and catenanes that have found applicationi nc atalysis, [87][88][89] molecular electronic devices [90,91] and drug delivery systems. [92] Figure 3.…”

Section: From Molecular Shuttles To Molecular Switchesmentioning

confidence: 99%

“…Based on the flood of reviews [24-27, 58, 63, 89, 118, 121] and feature articles, [147,148] not to mention remarkable, high-profile papers [43,53,56,61,87,88,94,108,112,128,135,136,144,146] and news & views, [95,129,137,145] that have surfaced in the scientific literature which enjoyg lamour status duringt he past couple of years, research into wholly synthetic molecular machines appearst o have reached at ippingp oint. If this point in the rise of molecular machines [24,25] has indeed been reached, then the questions which arise are what next and where next?T he latter question is the easier of the two to answer:i ft he history of science tells us anything, it is that applications which find their way into our everyday lives are ap rerequisite for the recognition of an ew field of science.…”

Section: Reflectionsmentioning

confidence: 99%

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Wholly Synthetic Molecular Machines

2016

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The past quarter of a century has witnessed an increasing engagement on the part of physicists and chemists in the design and synthesis of molecular machines de novo. This minireview traces the development of artificial molecular machines from their prototypes in the form of shuttles and switches to their emergence as motors and pumps where supplies of energy in the form of chemical fuel, electrochemical potential and light activation become a minimum requirement for them to function away from equilibrium. The challenge facing this rapidly growing community of scientists and engineers today is one of putting wholly synthetic molecules to work, both individually and as collections. Here, we highlight some of the recent conceptual and practical advances relating to the operation of wholly synthetic rotary and linear motors.

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Section: From Molecular Shuttles To Molecular Switchesmentioning

confidence: 99%

Section: Reflectionsmentioning

confidence: 99%

Wholly Synthetic Molecular Machines

2016

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“…Leigh and co‐workers also recently reported a rotaxane catalyst 142 that, unlike the previously described rotaxane catalysts, contains two catalytic sites (Scheme ) . The axle of the rotaxane contains both catalytic centers: a dibenzylamine part capable of iminium catalysis, as in previous catalysts, and a novel catalytic center consisting of a squaramide unit that can activate electrophiles through hydrogen bonding.…”

Section: Ion‐ and Neutral Molecule‐switchable Dynamic Catalystsmentioning

confidence: 99%

Dynamic Responsive Systems for Catalytic Function

Vlatković

Collins

Feringa

2016

Chemistry A European J

113

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Responsive systems have recently gained much interest in the scientific community in attempts to mimic dynamic functions in biological systems. One of the fascinating potential applications of responsive systems lies in catalysis. Inspired by nature, novel responsive catalytic systems have been built that show analogy with allosteric regulation of enzymes. The design of responsive catalytic systems allows control of catalytic activity and selectivity. In this Review, advances in the field over the last four decades are discussed and a comparison is made amongst the dynamic responsive systems based on the principles underlying their catalytic mechanisms. The catalyst systems are sorted according to the triggers used to achieve control of the catalytic activity and the distinct catalytic reactions illustrated.

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“…Notably, these two pairs of catalytic functional groups would also be addressed with two opposite helical chirality, P or M , upon irradiation and thermal relaxation. We envisioned such a design as a feasible future route for stimuli‐responsive switchable catalysts in multi‐tasking systems and one‐pot multi‐step diastereo‐ and enantioselective reactions …”

Section: Introductionmentioning

confidence: 99%

Bifunctional Molecular Photoswitches Based on Overcrowded Alkenes for Dynamic Control of Catalytic Activity in Michael Addition Reactions

Pizzolato

Collins

Leeuwen

et al. 2017

Chemistry A European J

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The emerging field of artificial photoswitchable catalysis has recently shown striking examples of functional light-responsive systems allowing for dynamic control of activity and selectivity in organocatalysis and metal-catalysed transformations. While our group has already disclosed systems featuring first generation molecular motors as the switchable central core, a design based on second generation molecular motors is lacking. Here, the syntheses of two bifunctionalised molecular switches based on a photoresponsive tetrasubstituted alkene core are reported. They feature a thiourea substituent as hydrogen-donor moiety in the upper half and a basic dimethylamine group in the lower half. This combination of functional groups offers the possibility for application of these molecules in photoswitchable catalytic processes. The light-responsive central cores were synthesized by a Barton-Kellogg coupling of the prefunctionalized upper and lower halves. Derivatization using Buchwald-Hartwig amination and subsequent introduction of the thiourea substituent afforded the target compounds. Control of catalytic activity in the Michael addition reaction between (E)-3-bromo-β-nitrostyrene and 2,4-pentanedione is achieved upon irradiation of stable-(E) and stable-(Z) isomers of the bifunctional catalyst 1. Both isomers display a decrease in catalytic activity upon irradiation to the metastable state, providing systems with the potential to be applied as ON/OFF catalytic photoswitches.

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Selecting reactions and reactants using a switchable rotaxane organocatalyst with two different active sites

Abstract: The activation mode of a rotaxane-based organocatalyst with both secondary amine and squaramide catalytic units can be switched with acid or base, affording different products from a mixture of three building blocks.

Cited by 134 publications

References 83 publications

Wholly Synthetic Molecular Machines

Wholly Synthetic Molecular Machines

Dynamic Responsive Systems for Catalytic Function

Bifunctional Molecular Photoswitches Based on Overcrowded Alkenes for Dynamic Control of Catalytic Activity in Michael Addition Reactions

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