Hydrosilylation of 1-pentyne by triethylsilane catalyzed by phosphine-rhodium complexes

Brady, Karen A.; Nile, Terence A.

doi:10.1016/s0022-328x(00)83027-2

Cited by 59 publications

(14 citation statements)

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“…Iridium complexes yield a mixture of cis-and trans-1-triethylsilylpent-1-enes from the hydrosilylation of pent-1-yne by triethylsilane. Like [RhCl(COE) 2 ] 2 , which also gives a mixture of the two pentenes with a cis:trans ratio of 61:29 [8], [IrCl(COE) 2 ] 2 gives a similar cis:trans ratio of 84:16 under the same conditions. This may be rationalized in terms of the mechanism proposed for rhodium catalysts [8] (Scheme 2).…”

Section: Results and Discussion 13-dienes And 1-alkynesmentioning

confidence: 99%

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Iridium complexes as hydrosilylation catalysts

Apple

Brady

Chance

et al. 1985

Journal of Molecular Catalysis

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Made available courtesy of Elsevier: http://www.elsevier.com/ ***Reprinted with permission. No further reproduction is authorized without written permission from Elsevier. This version of the document is not the version of record. Figures and/or pictures may be missing from this format of the document.*** Summary: Iridium complexes have been found to be active as catalysts for hydrosilylation reactions, especially for those involving 1,3-dienes and 1-alkynes. For ketones, iridium complexes show maximum activity if one molar equivalent (relative to iridium) of triphenylphosphine is added to the reaction mixture. Iridium complexes are also active catalysts for the hydrosilylation of α,β-unsaturated ketones, although the regioselectivity differs from that obtained with rhodium complexes. Attempts at asymmetric hydrosilylation of keto compounds using iridium complexes resulted in extremely low enantiomeric excesses.

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Section: Results and Discussion 13-dienes And 1-alkynesmentioning

confidence: 99%

“…These were carried out using standard procedures outlined in the literature [7,8]. Identification was by isolation and comparison of 1 H NMR and IR spectra with those of authentic samples, or by comparison of GLC retention times with those of authentic samples.…”

Section: Other Hydrosilylationsmentioning

confidence: 99%

Iridium complexes as hydrosilylation catalysts

Apple

Brady

Chance

et al. 1985

Journal of Molecular Catalysis

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“…This would lead to the coordinatively unsaturated species [RhCl(PPh 3 ) 2 ] or [RhCl(CO)PPh 3 )] which would be expected to show enhanced activity. The fact that a different catalytic species is involved is indicated by the change in ratio of cis: trans-olefin formed with the hydrosilylation of 1-pentyne by triethylsilane, a ratio which has been shown to be very sensitive to changes in catalyst (10) (Table 1).…”

Section: Rhodium Complexesmentioning

confidence: 99%

Organic peroxide assisted transition metal hydrosilylation catalysis

Calhoun

Lung

Nile

et al. 1983

Transition Met Chem

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Summary:The catalytic activity of rhodium complexes for the hydrosilylation of substrates such as alkenes, 1,3-dienes, 1-alkynes, or ketones, is enhanced by the addition of organic oxidizing agents, such as t-butyl hydroperoxide, hydrogen peroxide, or m-chloroperbenzoic acid. Similar enhancement is found for the Group VIA hexacarbonyls in the hydrosilylation of 1,3-dienes. Article: IntroductionThe concept of using a co-catalyst in conjunction with an inactive or weakly active transition metal complex is exemplified by the activation of transition metal salts by alkyl aluminum compounds to form the extensively used Ziegler-Natta systems (1) . These systems have been used to catalyze the hydrosilylation of a variety of unsaturated organic species, often with novel results (2) . Another type of co-catalysts which has been used, involves the oxidation of a ligand to form a weakly co-ordinating ligand oxide, thus generating a coordinatively unsaturated catalytically active complex (3)(4) . Oxidizing agents that have been used include molecular oxygen (in systems such as W(CO) 6 -EtAlCl 2 -O 2 for the metathesis of olefins (3) ) and peroxides [such as the system (PPh 3 ) 3 RhCl-H 2 O 2 for the hydrogenation of olefinsn . We have been investigating the use of co-catalysts such as organic peroxides or molecular oxygen and report here on our use of organic peroxides as co-catalysts in hydrosilylation reactions. During the course of our studies reports by others have appeared where an organic peroxide has been used as a co-catalyst for the hydrosilylation reaction (5,6) Results and Discussion Rhodium complexesWe have made use of bis(triphenylphosphine)carbonylchlororhodium(I), (1), as this is only moderately active for hydrosilylation reactions at room temperature (7) . As can be seen from Table 1, the activity of this catalyst is greatly increased by the addition of an approximately 50% molar excess of t-butyl hydroperoxide as co-catalyst. The activity increases by a factor of four to five for most combinations of organic unsaturate and silane. No attempt to optimize the reaction conditions was undertaken. The yields increase for the hydrosilylation of 1-octene by triethoxysilane, from 4% to 75% as the t-BuOOH : Rh ratio increases from zero to fifteen. (Table 2).The yield is maximized with respect to t-BuOOH: Rh ratio at a value of 7.4 :1. An optimum ratio of t-BuOOH : M (M = Rh, Ir) of 4 : 1 was observed for [RhCl(PPh 3 ) 3 ] or [IrCl-(CO)(PPh 3 ) 2 ] in hydrosilylation reactions, but decomposition of the catalysts was observed at higher t-BuOOH : M ratios (10 : 1) (6) . Decomposition was not observed in our case, the catalyst system remaining active at ratios of t-BuOOH : Rh of 15 :1. As the catalysts contain different ligands it is not surprising that their responses differ.The increase in activity has been attributed (6) to the oxidation of either co-ordinated carbon monoxide to weakly coordinating carbon dioxide, as has been shown to occur stoichiometrically (8) , or by oxidation of co-ordinated triphenylphosphine ...

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“…Although a majority of catalysts yield only the trans-olefin by cis-addition, it is becoming apparent that many rhodium catalysts produce mixtures of cis-and trans-olefins [6,8], and that the yields and ratios of isomers are sensitive to reaction conditions. In order to gain further insight into this reaction, a more detailed investigation of the hydrosilylation of 1-hexyne by triethylsilane catalyzed by II was carried out.…”

Section: Hydrosilylationmentioning

confidence: 99%

“…This implies either that addition takes place non-stereospecifically or that slow stereospecific addition takes place followed by rapid cis-trans isomerization. Previous work indicates that with other rhodium catalysts cis-trans isomerization does take place, but that it is slow compared to hydrosilylation [6,8]. The ratio of cis/trans adduct produced under identical conditions (100°C, 8 h) by I and II are similar (55/45 and 45/55, respectively), suggesting that electronic differences [9] between these ligands have little effect on this ratio, which is perhaps dominated by their similar steric bulk [9].…”

Section: Hydrosilylationmentioning

confidence: 99%