The recent synthesis and application of silicon-stereogenic silanes: A renewed and significant challenge in asymmetric synthesis

Xu, Li‐Wen; Li, Li; Lai, Guoqiao; Jiang, Jianxiong

doi:10.1039/c0cs00037j

Cited by 235 publications

(61 citation statements)

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“…They are commonly used in the form of polysiloxane "silicone" polymers as components of industrial and consumer products for a variety of purposes such as bulking agents, separation media, protective coatings, lubricants, emulsifiers, and adhesives (1)(2)(3). Their use as auxiliaries in the chemical synthesis of complex molecules is also long-established (4)(5)(6). However, the production and synthetic manipulation of these compounds are almost entirely dependent on chlorosilane feedstocks, which are environmentally undesirable and energyintensive to produce (7,8).…”

mentioning

confidence: 99%

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Dakhili

Caslin

Faponle

et al. 2017

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

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The family of silicatein enzymes from marine sponges (phylum Porifera) is unique in nature for catalyzing the formation of inorganic silica structures, which the organisms incorporate into their skeleton. However, the synthesis of organosiloxanes catalyzed by these enzymes has thus far remained largely unexplored. To investigate the reactivity of these enzymes in relation to this important class of compounds, their catalysis of Si-O bond hydrolysis and condensation was investigated with a range of model organosilanols and silyl ethers. The enzymes' kinetic parameters were obtained by a high-throughput colorimetric assay based on the hydrolysis of 4-nitrophenyl silyl ethers. These assays showed unambiguous catalysis with k cat /K m values on the order of 2-50 min. Condensation reactions were also demonstrated by the generation of silyl ethers from their corresponding silanols and alcohols. Notably, when presented with a substrate bearing both aliphatic and aromatic hydroxy groups the enzyme preferentially silylates the latter group, in clear contrast to nonenzymatic silylations. Furthermore, the silicateins are able to catalyze transetherifications, where the silyl group from one silyl ether may be transferred to a recipient alcohol. Despite close sequence homology to the protease cathepsin L, the silicateins seem to exhibit no significant protease or esterase activity when tested against analogous substrates. Overall, these results suggest the silicateins are promising candidates for future elaboration into efficient and selective biocatalysts for organosiloxane chemistry.silicatein | biocatalysis | organosilicon | organosiloxane | silyl ether T he organosiloxanes, compounds containing C-Si-O moieties, represent a class of compounds with a truly diverse range of applications. They are commonly used in the form of polysiloxane "silicone" polymers as components of industrial and consumer products for a variety of purposes such as bulking agents, separation media, protective coatings, lubricants, emulsifiers, and adhesives (1-3). Their use as auxiliaries in the chemical synthesis of complex molecules is also long-established (4-6). However, the production and synthetic manipulation of these compounds are almost entirely dependent on chlorosilane feedstocks, which are environmentally undesirable and energyintensive to produce (7,8). Furthermore, organosiloxanes, which are entirely anthropogenic in origin, are now known to be persistent environmental contaminants because little attempt is made to recover and recycle them (3). Synthetic routes that use, and ultimately recycle, siloxanes and silanols as alternatives would in principle be more environmentally sound.One possible strategy toward improved sustainability is to harness enzymes for chemical processing. Such biocatalysts are attractive because they offer highly efficient synthesis in terms of yields and regio-and stereospecificity, together with an ability to promote reactions under mild conditions and a minimal reliance on halogenated or metallic feedstocks (...

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confidence: 99%

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Dakhili

Caslin

Faponle

et al. 2017

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

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“…Unser mechanistisches Verständnis chemischer Reaktionen am Siliciumatom hängt in hohem Maße von unserer Fähigkeit ab, den stereochemischen Verlauf einer gegebenen Reaktion nachvollziehen zu können. Dazu werden herkömmlicherweise siliciumstereogene Silane verwendet (Abbildung 1, oben) 1. Im Rahmen seines wegweisenden und umfangreichen Forschungsprogramms zur Stereochemie des Siliciums erarbeitete Sommer unter Verwendung des chiralen Silans 1 und seiner Derivate einen Leitfaden für klassische Umsetzungen 2.…”

Section: Methodsunclassified

Eine Mischung deuteriummarkierter Silane als einfache mechanistische Sonde, die ohne Bestimmung von absoluten Konfigurationen auskommt

Fallon

Oestreich

2015

Angewandte Chemie

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Es wird über die Synthese und den Einsatz einer neuen stereochemischen Sonde für Mechanismen am Siliciumatom eines deuteriummarkierten Silolans berichtet. Der zentrale Syntheseschritt ist die Hydrierung eines 2,5‐Dihydrosilols mit Deuteriumgas, was zu einer komplexen Mischung isochroner Stereoisotopologe führt. Das gesamte stereochemische Ungleichgewicht dieser Mischung ist aus ihrem 2H‐NMR‐Spektrum ersichtlich, und das bietet ein gutes qualitatives Maß für Konfigurationsänderungen am Siliciumatom. Das Verfahren ist schnell, benutzerfreundlich und überwindet die Einschränkungen und Nebeneffekte klassischer Methoden. Die Nützlichkeit dieses neuen Instruments zum Verfolgen des stereochemischen Verlaufs von Bindungsknüpfungen am Siliciumatom wird anhand etlicher klassischer Reaktionen sowie aktueller katalytischer Umsetzungen veranschaulicht.

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“…Organosilicon compounds1 are of great importance in modern organic chemistry because of their usefulness in the protection of functional groups2 and their broad application in, for example, asymmetric synthesis,3 cross‐coupling reactions4 and natural product synthesis 5. This class of compounds and related siloxanes are the subject of continuously growing interest due to their ability to form oligomers,6 dendrimers7 and polymers8 and because of their unique properties, which have resulted in certain pivotal developments in the fields of silica‐supported catalysis,9 biosensors10 and material11 and nano sciences 12.…”

Section: Introductionmentioning

confidence: 99%

Sequential Synthesis of Organosilicon‐Linked 2‐Methoxypyridines by Non‐Cryogenic ortho‐Metallation Using the nBu₂TMPMg·Li Reagent and Hydrosilylation

et al. 2016

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The non‐cryogenic synthesis of 5/6‐ and/or 3‐silyl‐functionalised 2‐methoxypyridines by a 5‐Br/Mg exchange process using nBu2iPrMg Li and LiCl and involving C‐3 metallation using a novel nBu2TMPMg Li reagent is described. Furthermore, the usefulness of nBu2TMPMg Li in the functionalisation of 2‐methoxypyridine at the 3‐position with a wide range of electrophiles was successfully tested. The above achievements have allowed the construction of organosilicon‐linked 2‐methoxypyridines composed of two, three and four rings by the hydrosilylation of 5‐ and/or 3‐SiH(or alkenyl) derivatives using the hitherto rarely applied [Pt(cod)Me2] catalyst. Additionally, the synthesis of a one‐chain oligomer consisting of eight 2‐methoxypyridines obtained by the hydrosilylation/polymerisation approach, followed by protodesilylation of the SiHMe2 group was also achieved by manipulating the amount of catalyst in the reactions.

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The recent synthesis and application of silicon-stereogenic silanes: A renewed and significant challenge in asymmetric synthesis

Cited by 235 publications

References 156 publications

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Eine Mischung deuteriummarkierter Silane als einfache mechanistische Sonde, die ohne Bestimmung von absoluten Konfigurationen auskommt

Sequential Synthesis of Organosilicon‐Linked 2‐Methoxypyridines by Non‐Cryogenic ortho‐Metallation Using the nBu₂TMPMg·Li Reagent and Hydrosilylation

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The recent synthesis and application of silicon-stereogenic silanes: A renewed and significant challenge in asymmetric synthesis

Cited by 235 publications

References 156 publications

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Recombinant silicateins as model biocatalysts in organosiloxane chemistry

Eine Mischung deuteriummarkierter Silane als einfache mechanistische Sonde, die ohne Bestimmung von absoluten Konfigurationen auskommt

Sequential Synthesis of Organosilicon‐Linked 2‐Methoxypyridines by Non‐Cryogenic ortho‐Metallation Using the nBu2TMPMg·Li Reagent and Hydrosilylation

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Sequential Synthesis of Organosilicon‐Linked 2‐Methoxypyridines by Non‐Cryogenic ortho‐Metallation Using the nBu₂TMPMg·Li Reagent and Hydrosilylation