Catalysis of hydrosilylation

Addition of ethoxalyl chloride (ClCOCOOEt) to terminal alkynes at 60 degrees C in the presence of a rhodium(I)-phosphine complex catalyst chosen from a wide range affords 4-chloro-2-oxo-3-alkenoates regio- and stereoselectively. Functional groups such as chloro, cyano, alkoxy, siloxy, and hydroxy are tolerated. The oxidative addition of ethoxalyl chloride to [RhCl(CO)(PR(3))(2)] proceeds readily at 60 degrees C or room temperature and gives [RhCl(2)(COCOOEt)(CO)(PR(3))(2)] (PR(3) = PPh(2)Me, PPhMe(2), PMe(3)) complexes in high yields. The structure of [RhCl(2)(COCOOEt)(CO)(PPh(2)Me)(2)] was confirmed by X-ray crystallography. Thermolysis of these ethoxalyl complexes has revealed that those ligated by more electron-donating phosphines are fairly stable against decarbonylation and reductive elimination. [RhCl(2)(COCOOEt)(CO)(PPh(2)Me)(2)] reacts with 1-octyne at 60 degrees C to form ethyl 4-chloro-2-oxo-3-decenoate. The catalysis is therefore proposed to proceed by oxidative addition of ethoxalyl chloride, insertion of an alkyne into the Cl--Rh bond of the resulting intermediate, and reductive elimination of alkenyl-COCOOEt.

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“…[Rh 2 (cod) 2 Cl 2 ], [14] [RhCl(cod)(PR 3 )] [15] 2 ]. The other metal complexes were commercial products and used as received.…”

Section: Methodsmentioning

confidence: 99%

Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC₂H₅ to Alkynes

Hua

Onozawa

Tanaka

2005

Chemistry A European J

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“…As a model for [Rh(COD)Cl] 2 immobilized on siloxanes, 7,21 [Rh(COD)dpps Cl] was synthesized from a reaction of [Rh(COD)Cl] 2 and dpps in a molar ratio of 1:2 (Eq. 2)…”

Section: [Rh(cod)dppscl]mentioning

confidence: 99%

Silsesquioxanes as models of silica supported catalyst I. [3‐(Diphenylphosphino)propyl]‐hepta[propyl]‐[octasilsesquioxane] and [3‐mercapto‐propyl]‐hepta[propyl]‐[octasilsesquioxane] as ligands for transition‐metal ions

Hendan

Marsmann

1999

Appl. Organometal. Chem.

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“…Thus, they could be applied for various purposes. They were used as efficient catalysts in homogeneous reaction systems, − phase transfer catalysts, polymeric ligands for anchoring transition metal catalysts, − intermediates for chemical reactions, − polymer electrolytes, , ion extractants, , and materials for chromatography, as well as for other applications …”

Section: Introductionmentioning

confidence: 99%

Controlled Synthesis of Siloxane Copolymers Having an Organosulfur Group by Polymerization of Cyclotrisiloxanes with Mixed Units

Rózga-Wijas¹,

Chojnowski²,

Zundel³

et al. 1996

Macromolecules

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The preparation of poly(dimethylsiloxane)s having part of the siloxane units substituted with a model organic thioether was investigated. The sulfur group was generated by the ene−thiol addition to the vinyl function bound to silicon. Two synthetic routes to this copolymer were compared (i) one-step kinetically controlled polymerization of organosulfur-substituted hexamethylcyclotrisiloxane and (ii) two-step synthesis including kinetically controlled polymerization of 1,3,3,5,5-pentamethyl-1-vinylcyclotrisiloxane followed by the thiol addition to the vinyl group in the polymer. A cryptand−lithium silanolate complex generated from [(trimethylsilyl)methyl]lithium was selected as the initiator in this polymerization, while tert-butyl mercaptan was used as the hydrosulfidation reagent. It was shown that synthesis routes lead to a high yield of copolymers having a fairly regular chain structure. The arrangement of siloxane units in the polymer chain was controlled by the propagation step. Polymerization of the vinyl-substituted monomer exhibited a significant degree of regioselectivity as one of the three possible modes of the monomer ring opening contributed over 70% to the propagation. Addition of t-BuSH to the vinyl group in the polymer proceeded without rearrangement of the polymer chain and could be performed without any side reaction of the vinyl group. Model copolymers of regular alternating structure were synthesized by the heterofunctional polycondensation of [2-(tert-butylthio)ethyl]methyldichlorosilane with a series of diols, HO(Me2SiO) n H, n = 1−4. They were used for comparison with the copolymers obtained by ring-opening polymerization.

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Catalysis of hydrosilylation

Cited by 25 publications

References 14 publications

Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC₂H₅ to Alkynes

Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC₂H₅ to Alkynes

Silsesquioxanes as models of silica supported catalyst I. [3‐(Diphenylphosphino)propyl]‐hepta[propyl]‐[octasilsesquioxane] and [3‐mercapto‐propyl]‐hepta[propyl]‐[octasilsesquioxane] as ligands for transition‐metal ions

Controlled Synthesis of Siloxane Copolymers Having an Organosulfur Group by Polymerization of Cyclotrisiloxanes with Mixed Units

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Catalysis of hydrosilylation

Cited by 25 publications

References 14 publications

Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC2H5 to Alkynes

Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC2H5 to Alkynes

Silsesquioxanes as models of silica supported catalyst I. [3‐(Diphenylphosphino)propyl]‐hepta[propyl]‐[octasilsesquioxane] and [3‐mercapto‐propyl]‐hepta[propyl]‐[octasilsesquioxane] as ligands for transition‐metal ions

Controlled Synthesis of Siloxane Copolymers Having an Organosulfur Group by Polymerization of Cyclotrisiloxanes with Mixed Units

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Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC₂H₅ to Alkynes

Rhodium‐Catalyzed Nondecarbonylative Addition Reaction of ClCOCOOC₂H₅ to Alkynes