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• 694-53-1 phenylsilane 
• 108-94-1 cyclohexanone 

Relevant academic research and scientific papers

Hydrosilylation of Aldehydes and Formates Using a Dimeric Manganese Precatalyst

The formally zero-valent Mn dimer [(Ph2PEtPDI)Mn]2 has been synthesized upon reducing (Ph2PEtPDI)MnCl2 with excess Na/Hg. Single crystal X-ray diffraction analysis has revealed that [(Ph2PEtPDI)Mn]2 possesses a η4-PDI chelate about each Mn center, as well as η2-imine coordination across the dimer. The chelate metrical parameters suggest single electron PDI reduction and EPR spectroscopic analysis afforded a signal consistent with two weakly interacting S = 1/2 Mn centers. At ambient temperature in the absence of solvent, [(Ph2PEtPDI)Mn]2 has been found to catalyze the hydrosilylation of aldehydes at loadings as low as 0.005 mol % (0.01 mol % relative to Mn) with a maximum turnover frequency of 9,900 min-1 (4,950 min-1 per Mn). Moreover, the [(Ph2PEtPDI)Mn]2-catalyzed dihydrosilylation of formates has been found to proceed with turnover frequencies of up to 330 min-1 (165 min-1 relative to Mn). These metrics are comparable to those described for the leading Mn catalyst for this transformation, the propylene-bridged variant (Ph2PPrPDI)Mn; however, [(Ph2PEtPDI)Mn]2 is more easily inhibited by donor functionalities. Carbonyl and carboxylate hydrosilylation is believed to proceed through a modified Ojima mechanism following dimer dissociation.

Importance of co-donor field strength in the preparation of tetradentate α-diimine nickel hydrosilylation catalysts

Although bis(α-diimine)Ni complexes were prepared when amine-substituted chelates were added to Ni(COD)2, the incorporation of strong-field phosphine donors allowed the isolation of (κ4- N,N,P,P-DI)Ni hydrosilylation catalysts. The c

CpFe(CO)2anion-catalyzed highly efficient hydrosilylation of ketones and aldehydes

K[CpFe(CO)2] and [NEt4][CpFe(CO)2] enabled highly efficient hydrosilylation of ketones and aldehydes with PhSiH3 to synthesize tris- and bis(alkoxy)silanes in excellent yields depending on the substituents on the carbonyl compounds. The catalyst represent

Bench-Stable Cobalt Pre-Catalysts for Mild Hydrosilative Reduction of Tertiary Amides to Amines and Beyond

The readily synthesized and bench-stable cobalt dichloride complex (dpephos)CoCl2 is employed as a pre-catalyst for a diversity of silane additions to unsaturated organic molecules, including the normally challenging reduction of amides to amines. With regard to hydrosilative reduction of amides even more effective and activator free catalytic systems can be generated from the bench-stable, commercially available Co(acac)2 and Co(OAc)2 with dpephos and PPh3 ligands. These systems operate under mild conditions (100 °C), with many examples of room temperature transformations, presenting a first example of mild cobalt-catalyzed hydrosilylation of amides.

POCN Ni(ii) pincer complexes: Synthesis, characterization and evaluation of catalytic hydrosilylation and hydroboration activities

A series of iminophosphinite POCN pincer Ni(ii) complexes, (POCN)NiMe and (POCN)NiLn(BX4) (L = CH3CN, n = 0, 1; X = F, Ph, C6F5), have been developed and subjected to catalytic hydrosilylation of alkenes, aldehydes and ketones and hydroboration of carbonyl compounds. The stoichiometric reactivity of (POCN)NiMe and (POCN)Ni(BF4) with PhSiH3 and HBPin suggests that catalytic reactions proceed via the hydride intermediate (POCN)NiH. With regard to reactions with HBPin, efficient and mild hydroboration of a variety of carbonyl compounds, including highly chemoselective hydroboration of benzaldehyde in the presence of other common potent reductive functional groups, such as alkenes, alkynes, esters, amides, nitriles, nitro compounds and even ketones, and the first example of base metal catalyzed hydroboration of amides, including mild direct hydroborative reduction of primary and secondary amides to borylated amines were demonstrated for (POCN)NiMe.

Hydrosilylation of Aldehydes and Ketones Catalyzed by a Terminal Zinc Hydride Complex, [κ3-Tptm]ZnH

Tris(2-pyridylthio)methyl zinc hydride, [κ3-Tptm]ZnH, is an effective catalyst for multiple insertions of carbonyl groups into the Si-H bonds of PhxSiH4-x (x = 1, 2). Specifically, [κ3-Tptm]ZnH catalyzes the insertion of a variety of aldehydes and ketones into the Si-H bonds of PhSiH3 and Ph2SiH2 to afford PhSi[OCH(R)R′]3 and Ph2Si[OCH(R)R′]2, respectively. The mechanism for hydrosilylation is proposed to involve insertion of the carbonyl group into the Zn-H bond to afford an alkoxy species, followed by metathesis with the silane to release the alkoxysilane and regenerate the zinc hydride catalyst. Multiple insertion of prochiral ketones results in the formation of diastereomeric mixtures of alkoxysilanes that can be identified by NMR spectroscopy.

A Pentacoordinate Mn(II) Precatalyst That Exhibits Notable Aldehyde and Ketone Hydrosilylation Turnover Frequencies

Heating (THF)2MnCl2 in the presence of the pyridine-substituted bis(imino)pyridine ligand, PyEtPDI, allowed preparation of the respective dihalide complex, (PyEtPDI)MnCl2. Reduction of this precursor using excess Na/Hg resulted in deprotonation of the chelate methyl groups to yield the bis(enamide)tris(pyridine)-supported product, (κ5-N,N,N,N,N-PyEtPDEA)Mn. This complex was characterized by single-crystal X-ray diffraction and found to possess an intermediate-spin (S = 3/2) Mn(II) center by the Evans method and electron paramagnetic resonance spectroscopy. Furthermore, (κ5-N,N,N,N,N-PyEtPDEA)Mn was determined to be an effective precatalyst for the hydrosilylation of aldehydes and ketones, exhibiting turnover frequencies of up to 2475 min-1 when employed under solvent-free conditions. This optimization allowed for isolation of the respective alcohols and, in two cases, the partially reacted silyl ethers, PhSiH(OR)2 [R = Cy and CH(Me)(nBu)]. The aldehyde hydrosilylation activity observed for (κ5-N,N,N,N,N-PyEtPDEA)Mn renders it one of the most efficient first-row transition metal catalysts for this transformation reported to date.

A highly active manganese precatalyst for the hydrosilylation of ketones and esters

The reduction of (Ph2 PPrPDI)MnCl2 allowed the preparation of the formally zerovalent complex, (Ph2 PPrPDI)Mn, which features a pentadentate bis(imino)pyridine chelate. This complex is a highly active precatalyst for the hydrosilylation of ketones, exhibiting TOFs of up to 76,800 h-1 in the absence of solvent. Loadings as low as 0.01 mol % were employed, and (Ph2 PPrPDI)Mn was found to mediate the atom-efficient utilization of Si-H bonds to form quaternary silane products. (Ph2PPrPDI)Mn was also shown to catalyze the dihydrosilylation of esters following cleavage of the substrate acyl C-O bond. Electronic structure investigation of (Ph 2PPrPDI)Mn revealed that this complex possesses an unpaired electron on the metal center, rendering it likely that catalysis takes place following electron transfer to the incoming carbonyl substituent.

FIRST-ROW TRANSITION METAL HYDROGENATION AND HYDROSILYLATION CATALYSTS

Transition metal compounds, and specifically transition metal compounds having a tetradentate and/or pentadentate supporting ligand are described, together with methods for the preparation thereof and the use of such compounds as hydrogenation and/or hydrosilylation catalysts.

A remarkably active iron catecholate catalyst immobilized in a porous organic Polymer

A single-site, iron catecholate-containing porous organic polymer was prepared and utilized as a stable and remarkably active catalyst for the hydrosilylation of ketones and aldehydes. In some instances, catalyst loadings of 0.043-2.1 mol % [Fe] were sufficient for complete hydrosilylation of aldehydes and ketones within 15 min at room temperature. The catalyst can be recycled at least three times without a drop in catalytic activity. This system is an example of an immobilized homogeneous catalyst with no homogeneous analogue.