- Hammett ρ of reactions of MeLi with benzophenones
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Relative rates of reactions of MeLi with benzophenones in diethyl ether at 0 °C that furnish methyldiaryl-methanols were determined using slow addition of a MeLi solution to solutions containing an excess of two benzophenones. The additions exhibit a Hammett p of 0.94.
- Maclin, Keith M.,Richey Jr., Herman G.
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- Catalytic Enantioselective Addition of Aryl Grignard Reagents to Ketones
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We report a catalytic system for the challenging enantioselective addition of aryl Grignard reagents to ketones. Using a simple, one-pot procedure under mild conditions, a wide range of aromatic ketones are converted into diaryl alcohols in good yields and with good enantioselectivities. The catalytic enantioselective addition of aryl Grignard reagents to ketones is now possible. Using a readily available Ar-BINMOL ligand and titanium(IV) isopropoxide in a simple, one-pot procedure under mild conditions, a wide range of aromatic ketones are converted into diaryl alcohols in good yields and with good enantioselectivities.
- Fernández-Mateos, Emilio,Maciá, Beatriz,Yus, Miguel
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p. 6519 - 6526
(2016/02/18)
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- Continuous preparation of arylmagnesium reagents in flow with inline IR monitoring
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A newly developed microscale ReactIR flow cell was used as a convenient and versatile inline analytical tool for Grignard formation in continuous flow chemical processing. The LiCl-mediated halogen/Mg exchange reaction was used for the preparation of functionalized arylmagnesium compounds from aryl iodides or bromides. Furthermore, inline IR monitoring was used for the analysis of conversion and possible byproduct formation, as well as a potential tool for elucidation of mechanistic details. The results described herein indicate that the continuous flow systems are effective for highly exothermic reactions such as the Grignard exchange reaction due to fast mixing and efficient heat transfer.
- Brodmann, Tobias,Koos, Peter,Metzger, Albrecht,Knochel, Paul,Ley, Steven V.
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experimental part
p. 1102 - 1113
(2012/08/27)
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- Rhodium(I)/diene-catalyzed addition reactions of arylborons with ketones
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Rh(I)/diene-catalyzed addition reactions of arylboroxines/arylboronic acids with unactivated ketones to form tertiary alcohols in good to excellent yields are described. By using C2-symmetric (3aR,6aR)-3,6-diaryl-1,3a,4,6a- tetrahydropentalenes as ligands, the asymmetric version of such an addition reaction, with up to 68% ee, was also realized.
- Liao, Yuan-Xi,Xing, Chun-Hui,Hu, Qiao-Sheng
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supporting information; experimental part
p. 1544 - 1547
(2012/06/05)
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- C,O-dilithiated diarylmethanols: Easy and improved preparation by naphthalene-catalysed lithiation of diaryl ketones and reactivity toward electrophiles
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The lithiation of different diaryl ketones 1 with an excess of lithium powder and a catalytic amount (8 mol %) of naphthalene in tetradrofuran at -30°C leads to the formation of the corresponding dianions of the type I, with Met=Li, which react with several electrophiles (E+=MeI, EtBr, Pr(i)CHO, PhCHO, cyclohexanone, MeCN) to give, after hydrolysis, the expected substituted diarylmethanols 2.
- Guijarro,Mancheno,Yus
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p. 1327 - 1334
(2007/10/02)
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- Electron Transfer in Reactions of Ketones with Organolithium Reagents. A Carbon-14 Kinetic Isotope Effect Probe
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Kinetic isotope effects have been determined for reactions of ketones labeled with carbon-14 at the carbonyl carbon with MeLi and Me2CuLi in diethyl ether at 0 deg C.Observed isotope effects were as follows: (C6H5)2C=O + MeLi, 12k/14k = 1.000 +/- 0.002; (C6H5)2C=O + Me2CuLi, 1.029 +/- 0.005; 2,4,6-Me3C6H2COC6H5 + MeLi, 1.023 +/- 0.004.The relative reactivities of ortho-, meta-, and para-substituted benzophenones with these reagents were also determined by the competition experiments.These results are consistent with an electron transfer step which is followed by a carbon-carbon bond-formimg step that is or is not rate determining depending on the structure of ketones and reagents.The reaction of benzophenone with MeLi proceeds via rate-determining electron transfer; the change in nucleophile from MeLi to Me2CuLi shifts the rate-determining step from electron-transfer to recombination; the change in ketone from benzophenone to 2,4,6-trimethylbenzophenone also shifts the rate-determining step from electron transfer to recombination because the latter step becomes slower for the more hindered ketone.The extent of the geometrical change of the substrate at the electron-transfer transition state of the reaction of benzophenone with MeLi was estimated to be small on the basis of the magnitude of the KIE and teh ρ value of the Hammett correlation.
- Yamataka, Hiroshi,Fujimura, Naoya,Kawafuji, Yukie,Hanafusa, Terukiyo
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p. 4305 - 4308
(2007/10/02)
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