- Synthesis of silyl iron hydride: Via Si-H activation and its dual catalytic application in the hydrosilylation of carbonyl compounds and dehydration of benzamides
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The hydrido silyl iron complex (o-Ph2PC6H4SiMe2)Fe(PMe3)3H (2) was obtained via the activation of the Si-H bond of the bidentate silyl ligand o-Ph2P(C6H4)SiMe2H (1) by Fe(PMe3)4. 2 showed good to excellent catalytic activity in both the reduction of aldehydes/ketones and the dehydration of benzamide. In addition, with complex 2 as a catalyst, α,β-unsaturated carbonyls could be selectively reduced to the corresponding α,β-unsaturated alcohols. The mechanisms of the formation of 2 and the catalytic dehydration process are proposed and partly experimentally verified.
- Ren, Shishuai,Xie, Shangqing,Zheng, Tingting,Wang, Yangyang,Xu, Shilu,Xue, Benjing,Li, Xiaoyan,Sun, Hongjian,Fuhr, Olaf,Fenske, Dieter
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p. 4352 - 4359
(2018/03/26)
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- Syntheses of hydrido selenophenolato iron(II) complexes and their catalytic application in hydrosilylation of aldehydes and ketones
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Three novel selenophenolato hydrido iron(II) complexes [cis-(H)(SeAr)Fe(PMe3)4] (4–6) (Ar=C6H5 (4), p-MeOC6H4 (5) and o-MeC6H4 (6)) were prepared through the reaction of Fe(PMe3)4 with selenophenols ArSeH (1–3) via Se–H activation. The iron hydrido complexes 4, 5 and 6 could catalyze the hydrosilylation of aldehydes and ketones. Among them complex 5 is the best catalyst for this process. Furthermore, α,β-unsaturated alcohols could be obtained from the selective reduction reactions of the corresponding α,β-unsaturated carbonyls catalyzed by hydrido iron(II) complex 5. This catalytic system has good tolerance for some common groups but it is easy to reduce the nitro group to an amino group. The experiments indicate that the chemoselectivity for this catalytic system is –CHO>–NO2>–C([dbnd]O)CH3. The crystal structure of 6 was determined by X-ray diffraction.
- Wang, Yangyang,Ren, Shishuai,Zhang, Wenbo,Xue, Benjing,Qi, Xinghao,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
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- Synthesis and catalytic application of [PPP]-pincer iron, nickel and cobalt complexes for the hydrosilylation of aldehydes and ketones
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A new synthetic strategy for the novel diphosphine-phosphine oxide ligand (1) (Ph2P-(C6H4))2P(O)H was designed. A series of [PPP]-pincer Fe, Ni, and Co complexes were prepared. All of them were formed by chelate-assisted P-H activation. Two metal hydrides [(Ph2P-(C6H4))2P(O)]Fe(H)(PMe3)2 (2) and [(Ph2P-(C6H4))2P(O)]Ni(H)(PMe3) (3) were obtained at room temperature. The combination of ligand 1 with Co(PMe3)4Me or Co(PMe3)4 afforded the same Co(i) complex [(Ph2P-(C6H4))2P(O)]Co(PMe3)2 (4) via P-H bond activation. The catalytic performance of the Fe, Ni, and Co complexes for the hydrosilylation of aldehydes and ketones was explored. At a catalyst loading of 2 mol%, complex 2 displayed the best catalytic activity for the hydrosilylation by using (EtO)3SiH as the hydrogen source under mild conditions. Complexes 2, 3, and 4 were characterized by spectroscopic methods and X-ray diffraction analysis.
- Qi, Xinghao,Zhao, Hua,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
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p. 16583 - 16590
(2018/10/23)
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- Selective C-F and C-H Activation of Fluoroarenes by Fe(PMe3)4 and Catalytic Performance of Iron Hydride in Hydrosilylation of Carbonyl Compounds
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The reactions of perfluorinated toluene (CF3C6F5), pentafluoropyridine (C5NF5), and hexafluorobenzene (C6F6) with the iron(0) complex Fe(PMe3)4 were investigated. The Fe(I) complexes (4-CF3C6F4)Fe(PMe3)4 (1), (4-C5NF4)Fe(PMe3)4 (2), and (C6F5)Fe(PMe3)4 (3) were obtained by selective activation of the C-F bonds. However, under similar reaction conditions, the reaction of Fe(PMe3)4 with perfluoronaphthalene (C10F8) afforded a π-coordinated Fe(0) complex, (η4-1,2,3,4-C10F8)Fe(PMe3)3 (4), and the expected C-F bond activation reaction was not observed. The expected iron hydride (C6F5)FeH(PMe3)4 (6) could be obtained in a yield of 80% by the reaction of bromopentafluorobenzene with Fe(PMe3)4 and subsequent reduction with NaBH4. The molecular structures of complexes 2, 4, and 6 were determined by single-crystal X-ray diffraction. Complexes 1-4 and 6 could be used as catalysts for the hydrosilylation of carbonyl compounds. Among them, complex 6 is the best catalyst. The selective reduction of carbonyl groups of α,β-unsaturated aldehydes and ketones was also realized with 6 as catalyst.
- Zheng, Tingting,Li, Junye,Zhang, Shumiao,Xue, Benjing,Sun, Hongjian,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
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p. 3538 - 3545
(2016/11/06)
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- Dehydrogenative coupling of alcohols and carboxylic acids with hydrosilanes catalyzed by a salen-Mn(v) complex
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A Mn(v)-salen complex was found to be an effective catalyst for the dehydrogenative coupling of hydroxyl groups with hydrosilane. The reaction conditions were optimized with different silanes and efficient dehydrogenative coupling was achieved by using triethoxysilane and diphenylsilane. Various alcohols and phenols and a limited number of carboxylic acids were converted into the corresponding silyl ethers and silyl esters. A range of functional groups such as chloro, nitro, methoxy, carbonyl and carbon-carbon multiple bonds are tolerated in the reaction.
- Vijjamarri, Srikanth,Chidara, Vamshi K.,Rousova, Jana,Du, Guodong
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p. 3886 - 3892
(2016/06/14)
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- Synthesis of iron hydrides by selective C-F/C-H bond activation in fluoroarylimines and their applications in catalytic reduction reactions
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The reactions of Fe(PMe3)4 with different 2,6-diflurophenylarylimines 1-5 were explored. Fluoroarylimines 1-3, the aryl rings of which are substituted with electron-withdrawing groups, reacted with Fe(PMe3)4 to afford the C-H activation products 6-8. However, if the aryl rings of the fluoroarylimines were substituted with electron-donating groups, the iron hydrides 9 and 10 were obtained from the reactions of the fluoroarylimines with Fe(PMe3)4 through C-F bond activation. In a further study, silanes, especially triethoxysilane, were found to benefit the reactions and improve the yields of the hydridoiron complexes. The three-component reaction of Fe(PMe3)4, a fluoroarylimine, and a silane could also be utilized in reactions involving 2,6-(CH3)2C6H3-C(=NH)-2,6-F2C6H3 (13) and 2,6-F2C6H3-C(=NH)-C6F5 (16) to synthesize iron hydrides (15 and 18). The hydridoiron complexes could be utilized as efficient catalysts in the hydrosilylation of aldehydes and ketones. Furthermore, cinnamaldehydes were selectively reduced to the corresponding cinnamyl alcohols in high yields. The mechanism of the catalytic reduction reaction was studied extensively through operando IR spectroscopy.
- Wang, Lin,Sun, Hongjian,Li, Xiaoyan
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p. 2732 - 2743
(2015/06/22)
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- Unexpected role of zinc hydride in catalytic hydrosilylation of ketones and nitriles
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The hydride compound DippNacNacZnH (1) catalyzes chemoselective hydrosilylation of ketones and aldehydes under mild conditions and chemoselective reduction of nitriles to imines. Mechanistic studies showed that the product of nitrile insertion into the Zn
- Boone, Courtney,Korobkov, Ilia,Nikonov, Georgii I.
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p. 2336 - 2340
(2013/10/22)
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- HYDROSILYLATION OF CARBONYL COMPOUNDS CATALYZED BY SOLID ACIDS AND BASES
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Hydrosilylation of carbonyl compounds with hydrosilane is efficiently catalyzed by inorganic solid acids and bases such as Fe(3+) ion-exchanged montmorillonite and hydroxyapatite (Ca10(PO4)6(OH)2) at reaction temperatures between 25 and 90 deg C.Enones ar
- Izumi, Yusuke,Nanami, Hiroyuki,Higuchi, Katsumi,Onaka, Nakoto
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p. 4741 - 4744
(2007/10/02)
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