- Structural chemistry of alkali metal phenylhydrazides
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The crystal and molecular structures of a series of N-phenylsubstituted lithium hydrazides were determined in order to investigate possible Li...Ph π interactions. These are pronounced when there are no donor molecules present to solvate the Li centers. A
- Gemuend, Birgit,Noeth, Heinrich,Sachdev, Hermann,Schmidt, Martin
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- A synthetic and mechanistic investigation into the cobalt(i) catalyzed amination of aryl halides
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Employing first-row transition metals in catalytic two-electron transformations remains a synthetic challenge. In order to overcome the common and often deleterious single-electron reactivity, an electron rich ligand was targeted on cobalt. Herein, we report the Co(i) catalyzed amination of aryl halides with lithium hexamethyldisilazide. This transformation features (PPh3)3CoCl (1) as the catalyst and affords structurally diverse and electronically varied primary arylamines in good chemical yields, with the scope of the reaction featuring arylamines that cannot be synthesized via traditional metal-catalyzed amination routes, including 4-aminophenylboronic acid pinacol ester. Stoichiometric reactivity revealed that (PPh3)2CoN(SiMe3)2 (2) is likely generated within the catalytic cycle and could be independently synthesized from the reaction of (PPh3)3CoCl with LiN(SiMe3)2. Catalytic reactivity featuring the Co-amide complex, (PPh3)2CoN(SiMe3)2, showed that it is a competent catalyst, implying that the (PPh3)3CoCl may be serving as a pre-catalyst in the reaction. Both stoichiometric and kinetic studies support the catalytic cycle involving a Co(i) complex. Catalytic reactions featuring Co(ii) complexes resulted in undesired biaryl formation, a product that is not observed under standard catalytic conditions and any productive catalytic reactivity likely arises from an in situ reduction of Co(ii) to Co(i). A Hammett study was carried out to differentiate between a closed-shell or radical mechanism, the results of which are consistent with the proposed closed-shell mechanism. Initial studies indicate that this reactivity may be expanded to other bulky nucleophiles. This journal is
- Brennan, Marshall R.,Kim, Dongyoung,Fout, Alison R.
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p. 4831 - 4839
(2015/02/19)
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- Palladium catalysed aryl amination reactions in supercritical carbon dioxide
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Palladium catalysed C-N bond formation in supercritical carbon dioxide has been accomplished. Carbamic acid formation is avoided in part through the use of an N-silylamine as the coupling partner. Employing a catalyst system of Pd 2dba3 (1 mol%) and 2-dicyclohexylphosphino-2′, 4′,6′-triisopropyl-1,1′-biphenyl (X-Phos) (2 mol%) enabled the catalytic amination of aryl bromides and chlorides with N-silylanilines to be realised in excellent yield. Extension of the methodology to the N-arylation of N-silyldiarylamines, N-silylazoles and N-silylsulfonamides is reported. The Royal Society of Chemistry 2005.
- Smith, Catherine J.,Tsang, Melanie W.S.,Holmes, Andrew B.,Danheiser, Rick L.,Tester, Jefferson W.
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p. 3767 - 3781
(2007/10/03)
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- HeI and HeII photoelectron spectroscopic investigation of substituent effects in aminosilanes
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The HeI and HeII ultraviolet photoelectron spectra of PhΦNH, PhNHSiMe3, PhΦNSiMe3, (PhΦN)2SiMe2, Ph2NSiMe2Φ, Ph2NSiPh3 and Ph2NSiΦ3 (Me = CH3; Ph = C6H5; Φ = C6F5) are reported.Tentative assignment is given for the low-IE (ionization energy) region.HeI an
- Nagy, Attila,Green, Jennifer C.,Szepes, Laszlo,Zanathy, Laszlo
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- NOVEL TRICHLOROACETYL BASED SILYLATIONS: SIMPLE METHODS FOR t-BUTYLDIMETHYLSILYLATIONS AND FOR THE PROTECTION OF AMINO GROUPS.
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A new reagent for t-butyldimethylsilylation has been developed and the known trimethylsilyl trichloroacetate (1) has been shown to be of use for N-silylating amines.
- Galan, Adam A.,Lee, Thomas V.,Chapleo, Christopher B.
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p. 4995 - 4998
(2007/10/02)
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- CYANIDE-ION-CATALYZED REACTION OF PENTAFLUOROPHENYLTRIMETHYLSYLANE WITH SUBSTITUTED ACETOPHENONES
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Treatment of pentafluorophenyltrimethylsilane (I) with enolizable ketones in the presence of catalytic amount of potassium cyanide-18-crown-6 complex gave the corresponding trimethylsilyl enol ethers.The same dehydrogenative silylation of highly crowded 2
- Vyazankina, O. A.,Gostevskii, B. A.,Vyazankin, N. S.
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p. 145 - 150
(2007/10/02)
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