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New axial N,N′-dioxide secondary amide derived from l-tryptophan was synthesized and firstly employed in catalytic enantioselective reduction of ketoimines with trichlorosilane. It was found that 4f was an effective catalyst with excellent reactivity and good enantioselectivity. Possible mechanism for the catalytic procedure was tentatively proposed. 相似文献
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TrichlorosilaneisanimportantmaterialinplasmaChemicalVaporDeposition (CVD)andinsemiconductordeviceprocess .1 4 Thereactionoftrichlorosilanewithatomichydrogen ,thesimplestfree radicalspecies,hasdrawnconsiderableattention :kineticparametersforH atomreactionared… 相似文献
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The high surface area of porous silica gel enables characterization of the amount of adsorbed water needed for horizontal polymerization of trichlorosilanes for the first time. Silica gel samples were individually exposed to relative humidity levels of 30%, 40%, 50% and 60% prior to reaction, and the amount of adsorbed water was determined by weighing. Optical microscopy shows that polymer microspheres, unattached to the silica, form in the case of 60% humidity, indicating that this level is in excess of the optimum coverage of water. Microanalysis reveals a monotonic increase in carbon with increased humidity, and 29Si NMR spectra reveal increased cross-linking of the siloxanes as the humidity increased to 50%. HPLC is shown to be a very sensitive technique for assessing the coverage of the silica substrate: zone tailing is sharply minimized at 50% humidity. These results point to 50% as the optimal humidity for dense horizontal polymerization of trichlorosilanes. The amount of adsorbed water at 50% humidity and room temperature is 22±3 μmol/m2, which approaches the stoichiometric amount required to hydrolyze the trichlorosilanes. 相似文献
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Dong Euy Jung Seung-Hyun Kang Weon Cheol Lim Bok Ryul Yoo 《Journal of organometallic chemistry》2007,692(18):3901-3906
Coupling reaction of polychloromethanes CH4−nCln (n = 2-4) with HSiCl3 in the presence of tetrabutylphosphonium chloride (Bu4PCl) as a catalyst occurred at temperatures ranging from 30 °C to 150 °C. The reactivity of polychloromethanes increases as the number of chlorine-substituents on the carbon increases. In the reactions of CCl4 with HSiCl3, a variety of coupling products such as bis(chlorosilyl)methanes CH2(SiCl3)(SiXCl2) [X = Cl (1a), H (1b)], (chlorosilyl)trichloromthanes Cl3CSiXCl2 [X = Cl (2a), H (2b)], and (chlorosilyl)dichloromthanes Cl2HCSiXCl2 [X = Cl (3a), H (3b)] were obtained along with reductive dechlorination products such as CHCl3 and CH2Cl2 depending on the reaction temperature. In the reaction of CCl4, 2a is formed at the initial stage of the coupling reaction and converted to give CHCl3 at low temperature of 30 °C, to give 1a, 3a, and CHCl3 at 60 °C, and to afford 1a as major product and CH2Cl2 in competition above 100 °C. Si-H bond containing silylmethanes can be formed by the H-Cl exchange reaction with HSiCl3. Reaction of CHCl3 with HSiCl3 took placed at 80 °C to give three compounds 1a, 3a, and CH2Cl2, and finally 3a was converted to give 1a and CH2Cl2 at longer reaction time. While the condition for the reaction of CH2Cl2 with HSiCl3 required a much higher temperature of 150 °C. Under the optimized conditions for synthesizing bis(chlorosilyl)methanes 1a,b, a mixture of 1a and 1b were obtained as major products in 65% (1a:1b = 64:1) and 47% (42:5) yields from the reaction of CCl4 and CHCl3 at 100 °C for 8 h, respectively, and in 41% (34:7) yield from that of CH2Cl2 at 170 °C for 12 h. In the Si-C coupling reaction of polychloromethanes with HSiCl3, it seems likely that a trichlorosilyl anion generated from the reaction of HSiCl3 with Bu4PCl is an important key intermediate. 相似文献
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The reaction of aldehydes, enamines, and trichlorosilane in the presence of a Lewis base catalyst, particularly N-methylpyrrolidinone and DMF, affords γ-amino alcohols with a high diastereoselectivity. The method consists of C-C bond formation between an aldehyde and an enamine, and a subsequent intramolecular reduction of the resulting iminium ion intermediate. In most cases, one diastereomer is exclusively generated, and we propose a transition state model for the intramolecular reduction of the iminium ion intermediate. Enamines, prepared beforehand from the corresponding ketone and amine, can be used in the reaction without purification. Furthermore, enantioselective catalysis using a chiral Lewis base catalyst is possible, although the enantioselectivity is modest. The current tandem method offers the first, concise synthetic method of γ-amino alcohols from aldehydes and enamines. 相似文献
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Asymmetric reduction of prochiral ketimines 1a-f with trichlorosilane can be catalyzed by the Lewis-basic formamides (S)-4a,b, derived from N-methyl valine, with ≤91% enantioselectivity and low catalyst loading (≤5 mol %) at room temperature in toluene. 相似文献
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《Tetrahedron》2019,75(36):130495
A series of axially chiral biscarboline-based sulfones were synthesized from l-tryptophane and applied for enantioselective 1,2-transfer hydrogenations of ketimines using trichlorosilane. The catalyst 4e, which had a tertiary butyl group, exhibited a good conversion and high enantioselectivities up to 96%ee in the series of reactions. 相似文献
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以L-色氨酸为原料合成了5个伯酰胺结构的轴手性双咔啉N—O催化剂N2,N2'-二氧-9,9'-二甲基-3,3'-取代甲酰胺-β-双咔啉(4A~4E),并用于不对称催化酮亚胺的还原反应.结果表明,催化剂的催化转化率较高(80%~98%),立体选择性(e.e.值)较好,其中催化剂N2,N2'-二氧-9,9'-二甲基-3,3'-环己基甲酰胺-β-双咔啉(4B)的催化转化率达到了98%,e.e.值达68%. 相似文献