Increased Catalytic Activity of Surface‐Immobilized Palladium Complexes in the Fluorogenic Deprotection of an Alloc‐Derivatized Coumarin

Fernandes, Antony E.; Hensenne, Peter; Mathy, Bertrand; Guo, Weiming; Nysten, Bernard; Jonas, Alain M.; Riant, Olivier

doi:10.1002/chem.201102245

Cited by 11 publications

(20 citation statements)

References 37 publications

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“…Total TONs are finally ≲3500, consistent with the observed limit of our catalyst. As previously observed,9g the progressive deactivation of the catalytic PBs is mainly attributed to the gradual leaching of palladium. A simple regeneration process allowed used samples, after being reloaded by immersion in [Pd(OAc) 2 ] solution, to almost recover their initial potential.…”

Section: Resultssupporting

confidence: 78%

“…The influence of the solvent was not examined in this work as we have previously observed9g that the outcome of our model reaction is strongly dependent on the nature of the solvent. Thus, this renders the approximation of solvent‐triggered architectural effects (swollen/collapsed PBs) particularly complicated.…”

Section: Resultsmentioning

confidence: 99%

“…The system was kept under argon for 20 h without stirring. Conversions were determined by 1 H NMR spectroscopy 9g…”

Section: Methodsmentioning

confidence: 99%

“…In our endeavor to explore the operation of catalytically active silicon surfaces, we envisioned the use of PBs as supports for homogeneous organometallic complexes. The systems presented herein were prepared by the complexation of [Pd(OAc) 2 ] to pendant dipyridylamine (dpa) ligands incorporated on to PBs of various thicknesses and evaluated in a model reaction based on the palladium(0)‐mediated deprotection of Alloc‐coumarin 1 (Scheme ) 9g…”

Section: Introductionmentioning

confidence: 99%

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Thicker is Better? Synthesis and Evaluation of Well‐Defined Polymer Brushes with Controllable Catalytic Loadings

Fernandes

Dirani

D'Haese

et al. 2012

Chemistry A European J

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Polymer brushes (PBs) have been used as supports for the immobilization of palladium complexes on silicon surfaces. The polymers were grown by surface-initiated atom-transfer radical polymerization (SI-ATRP) and postdecorated with dipyridylamine (dpa) ligands. The pendant dpa units were in turn complexed with [Pd(OAc)(2)] to afford hybrid catalytic surfaces. A series of catalytic samples of various thicknesses (ca. 20-160 nm) and associated palladium loadings (ca. 10-45 nmol cm(-2)) were obtained by adjusting the SI-ATRP reaction time and characterized by ellipsometry, X-ray reflectivity, X-ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS). ICP-MS revealed a near-linear relationship between thickness of the polymer brush and palladium content, which confirmed the robustness of the preparation and postmodification sequence presented herein, rendering possible the creation of functional architectures with predefined catalytic potential. The activities of the catalytic PBs were determined by systematically exploring a full range of substrate-to-catalyst ratios in a model palladium(0)-catalyzed reaction. Quantitative transformations were observed for loadings down to 0.03 mol % and a maximum turnover number (TON) of around 3500 was established for the system. Comparison of the catalytic performances evidenced a singular influence of the thickness on conversions and TONs. The limited recyclability of the hairy catalysts has been attributed to palladium leaching.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 99%

“…The system was kept under argon for 20 h without stirring. Conversions were determined by 1 H NMR spectroscopy 9g…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thicker is Better? Synthesis and Evaluation of Well‐Defined Polymer Brushes with Controllable Catalytic Loadings

Fernandes

Dirani

D'Haese

et al. 2012

Chemistry A European J

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“…Recently, a report was published on allyloxycarbonyl (Alloc) removal catalyzed by palladium immobilized on a silicon surface. 8 We wished to develop a methodology involving supported catalysis that could be applied to general allyl ester removal with the aim of simplifying or, ideally, removing the chromatographic purification step. Here, we report the results of our investigation and demonstrate that, once optimized, the approach could be used in the synthesis of orthogonally protected L-octaarginine.…”

mentioning

confidence: 99%

Synthesis of l-Octaarginine through Microencapsulated Palladium-Catalyzed Allyl Ester Deprotection

Pérez‐López

González-Calderón

Occorso

et al. 2014

Synlett

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Octaarginine has been described as a molecular transporter. We report a useful synthesis of orthogonally protected L-octaarginine by using a method based on a microencapsulated palladium catalyst. Known palladium-based methods for allyl ester deprotection have been modified to facilitate purification of the unprotected intermediates. This improvement in the purification step has also been tested with a variety of allyl α-amino esters and allyl α,β-unsaturated esters.

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Effects of Thickness and Grafting Density on the Activity of Polymer‐Brush‐Immobilized Tris(triazolyl) Copper(I) Catalysts

Fernandes

Collard

et al. 2015

ChemCatChem

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We report herein the application of polymer brushes for the immobilization of tris[(1,2,3‐triazolyl)methyl]amine CuCl catalysts. Well‐defined catalytic brushes were prepared through grafting‐from and postpolymerization modification approaches on Si surfaces and characterized by X‐ray reflectivity, X‐ray photoelectron spectroscopy, and inductively coupled plasma mass spectrometry. Hairy catalysts of varying thickness and grafting density were investigated in a model CuI‐catalyzed azide–alkyne cycloaddition reaction and showed remarkable activity at loadings as low as 0.02 mol % as a result of the unique catalytic site density and nuclearity found in the brush. We demonstrate that thickness and grafting density parameters can be adjusted to maximize catalytic activity along the brush thickness.

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Increased Catalytic Activity of Surface‐Immobilized Palladium Complexes in the Fluorogenic Deprotection of an Alloc‐Derivatized Coumarin

Cited by 11 publications

References 37 publications

Thicker is Better? Synthesis and Evaluation of Well‐Defined Polymer Brushes with Controllable Catalytic Loadings

Thicker is Better? Synthesis and Evaluation of Well‐Defined Polymer Brushes with Controllable Catalytic Loadings

Synthesis of l-Octaarginine through Microencapsulated Palladium-Catalyzed Allyl Ester Deprotection

Effects of Thickness and Grafting Density on the Activity of Polymer‐Brush‐Immobilized Tris(triazolyl) Copper(I) Catalysts

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