ChemInform Abstract: Fast and Selective Oxidation of Primary Alcohols to Aldehydes or to Carboxylic Acids and of Secondary Alcohols to Ketones Mediated by Oxoammonium Salts Under Two‐Phase Conditions.

Anelli, Pier Lucio; Biffi, C.; Montanari, Fernando; Quici, Silvio

doi:10.1002/chin.198749121

Cited by 16 publications

(28 citation statements)

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“…This novel method uses simple approaches and avoids potential harmful substances [27][28][29][30][31]; hence it is a facile and green approach to prepare iron oxide-based magnetic nanocomposite materials with efficient immobilization of TEMPO. The product was investigated as catalyst for alcohols/aldehydes or ketone transformation under both the Anelli [34] and Minisci [35] protocols.…”

Section: International Journal Of Polymer Sciencementioning

confidence: 99%

Facile TEMPO Immobilization onto Poly(acrylic acid)-Modified Magnetic Nanoparticles: Preparation and Property

Huang

Liu

Bei

et al. 2017

International Journal of Polymer Science

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Adding catalysts to magnetic polyvalent supports facilitating catalyst recycling and recovery seems feasible. Polymer-modified magnetic nanocomposites for organocatalyst immobilization are a plausible approach to this technology. Here, we present facile and efficient method for 2,2 ,6,6 -tetramethylpiperidinyl-1-oxy (TEMPO) immobilization onto polymer-modified magnetic nanoparticles under mild reaction conditions. Poly(acrylic acid) was chosen to graft from magnetic nanoparticle through a simple inverse emulsion polymerization technique. The resulting poly(acrylic acid) magnetic nanocomposite is an ideal material to immobilize the organocatalyst 4-hydroxy-2,2 ,6,6 -tetramethylpiperidinyl-1-oxy (H-TEMPO) via an esterification reaction with pendant carboxyl group on the polymer chain. Instrumental analysis confirmed that poly(acrylic acid) chain was grafted on the silica-coated magnetic particles by this simple method while maintaining their magnetic properties; elemental analysis indicated that TEMPO was efficiently immobilized onto the polymer chain. The catalysis tests under both Anelli and Minisci system showed that the nanocomposite catalyst exhibits proper selectivity and activity for the alcohol/aldehyde transformation. Recycling experiments showed that stability and reusability of the nanocomposite catalyst were satisfying.

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Section: International Journal Of Polymer Sciencementioning

confidence: 99%

Facile TEMPO Immobilization onto Poly(acrylic acid)-Modified Magnetic Nanoparticles: Preparation and Property

Huang

Liu

Bei

et al. 2017

International Journal of Polymer Science

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“…The OKR reactions were performed in a biphasic mixture consisting of the catalytic peptoid (1 mol % based on the 1-phenylethanol substrate) dissolved in dichloromethane, an aqueous solution of KBr (0.5 M), and 1-phenylethanol (typically 1 ϫ 10 Ϫ4 mol). The oxidation reaction commenced upon addition of an aqueous solution containing 0.5 M sodium hypochlorite (26) …”

Section: Synthesis and Characterization Of Peptoids Incorporating Temmentioning

confidence: 99%

“…We evaluate a family of peptoid oligomers as catalysts for the OKR of racemic mixtures of chiral secondary alcohols (20)(21)(22)(23), which often appear in natural products and are valuable as enantiopure synthetic intermediates for specialty chemicals, including pharmaceuticals and agrochemicals (24,25). Specifically, we describe the OKR of 1-phenylethanol, which has been used as a benchmark for this transformation (26)(27)(28).…”

mentioning

confidence: 99%

Folded biomimetic oligomers for enantioselective catalysis

Maayan

Ward

Kirshenbaum

2009

Proc. Natl. Acad. Sci. U.S.A.

188

143

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Many naturally occurring biopolymers (i.e., proteins, RNA, DNA) owe their unique properties to their well-defined three-dimensional structures. These attributes have inspired the design and synthesis of folded architectures with functions ranging from molecular recognition to asymmetric catalysis. Among these are synthetic oligomeric peptide (''foldamer'') mimics, which can display conformational ordering at short chain lengths. Foldamers, however, have not been explored as platforms for asymmetric catalysis. This report describes a library of synthetic helical ''peptoid'' oligomers that enable enantioselective transformations at an embedded achiral catalytic center, as illustrated by the oxidative kinetic resolution of 1-phenylethanol. In an investigation aimed at elucidating key structure-function relationships, we have discovered that the enantioselectivity of the catalytic peptoids depends on the handedness of the asymmetric environment derived from the helical scaffold, the position of the catalytic center along the peptoid backbone, and the degree of conformational ordering of the peptoid scaffold. The transfer of chiral information from a folded scaffold can enable the use of a diverse assortment of embedded achiral catalytic centers, promising a generation of synthetic foldamer catalysts for enantioselective transformations that can be performed under a broad range of reaction environments.catalyst ͉ foldamer ͉ oxidative kinetic resolution ͉ peptoid T he unique capabilities of biopolymers, which stem from their well-defined three-dimensional structures, have been a source of inspiration for the design and synthesis of functional chemical systems (1). A variety of strategies have been explored for de novo construction of modular catalysts that enable chemical selectivity, regioselectivity, or enantioselectivity as a consequence of their structural organization. For example, synthetic peptides equipped with catalytic artificial amino acid groups or transition metal sites have been demonstrated to be effective enantioselective catalysts due to the proximity of the catalytic sites to the asymmetric environment created by their backbone (2-4). Similarly, it has been reported that nucleic acids can be used as chiral scaffolds for asymmetric synthesis and catalysis (5, 6). A recent investigation of DNA-based asymmetric catalysis relies on the noncovalent association of an achiral metal catalyst at unspecified sites along a DNA backbone, creating a chiral environment about the catalytic center that results in enantioselective transformations (7,8). Despite these advances, there remains a need for robust systems that permit rational design of versatile sequences and facile synthesis of libraries for high-throughput screening and optimization of catalytic performance.In living systems, biopolymer catalysts have evolved to accelerate specific biologically relevant transformations. In contrast, synthetic catalysts must often be designed for nonbiological transformations to be performed in abiotic solvents, pH regime...

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“…P ersistent nitroxides have intriguing structural and chemical properties [1][2][3] and possess a multitude of highly important applications, such as oxidation catalysts [4][5][6][7] , reagents in living polymerization reactions 8 , spin probes in biology 9 , radical traps in mechanistic investigations, spin trapping agents, medicinal agents 10,11 and in materials chemistry 12 . Designing and preparing stable nitroxides, as well as predicting their properties, remains an important challenge that must be met through a combination of computational methods and creativity 12 .…”

mentioning

confidence: 99%

“…TEMPO (3) is a shelf-stable compound and is the catalyst of choice in industry 14 as well as in academia for the oxidation of primary alcohols to aldehydes [1][2][3][4][5][6][7] . It has many applications in evaluating radical formation in biological tissues 15,16 and is also the trapping agent of choice in mechanistic investigations of chemical processes when a radical intermediate is suspected 17,18 .…”

mentioning

confidence: 99%

Design concept for α-hydrogen-substituted nitroxides

et al. 2015

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Stable nitroxides (nitroxyl radicals) have many essential and unique applications in chemistry, biology and medicine. However, the factors influencing their stability are still under investigation, and this hinders the design and development of new nitroxides. Nitroxides with tertiary alkyl groups are generally stable but obviously highly encumbered. In contrast, a-hydrogen-substituted nitroxides are generally inherently unstable and rapidly decompose. Herein, a novel, concept for the design of stable cyclic a-hydrogen nitroxides is described, and a proof-of-concept in the form of the facile synthesis and characterization of two diverse series of stable a-hydrogen nitroxides is presented. The stability of these unique a-hydrogen nitroxides is attributed to a combination of steric and stereoelectronic effects by which disproportionation is kinetically precluded. These stabilizing effects are achieved by the use of a nitroxide co-planar substituent in the g-position of the backbone of the nitroxide. This premise is supported by a computational study, which provides insight into the disproportionation pathways of a-hydrogen nitroxides.

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ChemInform Abstract: Fast and Selective Oxidation of Primary Alcohols to Aldehydes or to Carboxylic Acids and of Secondary Alcohols to Ketones Mediated by Oxoammonium Salts Under Two‐Phase Conditions.

Cited by 16 publications

References 1 publication

Facile TEMPO Immobilization onto Poly(acrylic acid)-Modified Magnetic Nanoparticles: Preparation and Property

Facile TEMPO Immobilization onto Poly(acrylic acid)-Modified Magnetic Nanoparticles: Preparation and Property

Folded biomimetic oligomers for enantioselective catalysis

Design concept for α-hydrogen-substituted nitroxides

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