- Triphosgene and DMAP as Mild Reagents for Chemoselective Dehydration of Tertiary Alcohols
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The utility of triphosgene and DMAP as mild reagents for chemoselective dehydration of tertiary alcohols is reported. Performed in dichloromethane at room temperature, this reaction is readily tolerated by a broad scope of substrates, yielding alkenes preferentially with the (E)-geometry. While formation of the Hofmann products is generally favored, a dramatic change in alkene selectivity toward the Zaitzev products is observed when the reaction is carried out in dichloroethane at reflux.
- Ganiu, Moshood O.,Cleveland, Alexander H.,Paul, Jarrod L.,Kartika, Rendy
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supporting information
p. 5611 - 5615
(2019/08/01)
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- Generation of Aryl and Heteroaryl Magnesium Reagents in Toluene by Br/Mg or Cl/Mg Exchange
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The alkylmagnesium alkoxide sBuMgOR?LiOR (R=2-ethylhexyl), which was prepared as a 1.5 m solution in toluene, undergoes very fast Br/Mg exchange with aryl and heteroaryl bromides, producing aryl and heteroaryl magnesium alkoxides (ArMgOR?LiOR) in toluene. These Grignard reagents react with a broad range of electrophiles, including aldehydes, ketones, allyl bromides, acyl chlorides, epoxides, and aziridines, in good yields. Remarkably, the related reagent sBu2Mg?2 LiOR (R=2-ethylhexyl) undergoes Cl/Mg exchange with various electron-rich aryl chlorides in toluene, producing diorganomagnesium species of type Ar2Mg?2 LiOR, which react well with aldehydes and allyl bromides.
- Ziegler, Dorothée S.,Karaghiosoff, Konstantin,Knochel, Paul
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supporting information
p. 6701 - 6704
(2018/05/05)
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- A Short Access to Symmetrically α,α-Disubstituted α-Amino Acids from Acyl Cyanohydrins
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A straightforward synthesis of symmetrically α,α-disubstituted α-amino acids is presented. The key step of this process relies on the efficient double addition of Grignard reagents to acyl cyanohydrins to provide N-acyl amino alcohols selectively in good yields. The chemoselectivity of the reaction was modulated by the nature of the acyl moiety. Eleven amino acids were prepared, including the particularly simple divinylglycine, which is not easily accessible by using conventional methods.
- Boukattaya, Fatma,Caillé, Julien,Ammar, Houcine,Rouzier, Florian,Boeda, Fabien,Pearson-Long, Morwenna S. M.,Bertus, Philippe
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p. 906 - 916
(2016/03/12)
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- COMPOUNDS FOR INHIBITING KSP KINESIN ACTIVITY
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The present invention provides compounds of Formula (I) (wherein R1, R3, X, W, Z and ring Y are as defined herein). The present invention also provides compositions comprising these compounds that are useful for treating cellular proliferative diseases or disorders associated with KSP kinesin activity and for inhibiting KSP kinesin activity.
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Page/Page column 89
(2010/11/23)
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- Unexpected formation of aryl dialkyl carbinol as a side product from the reaction of methoxyarylaldehydes with Grignard reagents
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In the attempted formation of secondary aryl alkyl carbinols from the reaction of methoxyarylaldehydes with Grignard reagents, aryl dialkyl carbinols were formed as unexpected side products. A mechanism for their formation is proposed.
- Sharma, Anuj,Joshi, Bhupendra P.,Singh, Narendra P.,Sinha, Arun K.
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p. 847 - 851
(2007/10/03)
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- Arene-catalysed lithiation of fluoroarenes
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The reaction of different fluoroarenes 1 with lithium and a catalytic amount (7%) of naphthalene in THF at -30°C affords the corresponding aryllithium intermediates which, by reaction with several electrophiles at temperatures ranging between -30 and 0°C, lead to the expected products 2, after hydrolysis. (C) 2000 Elsevier Science Ltd.
- Guijarro, David,Yus, Miguel
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p. 1135 - 1138
(2007/10/03)
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- Steric Effects in Photochemical Cycloadditions of 9-Phenanthrenecarboxylates
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Efficiency of photochemical intramolecular and intermolecular cycloadditoin of 9-phenanthrenecarboxylate-anethole systems is dependent on the structure of anethole moiety.Reduction in reactivity of the anethole moiety by steric effects is explained in terms of decrease in coefficients of frontier orbitals on the double bond due to twisting of the anisyl moiety.
- Itoh, Hiroki,Shibata, Hirofumi,Wagatsuma, Marie,Nanjoh, Mari,Senda, Yasuhisa,et al.
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p. 340 - 343
(2007/10/02)
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- Steric and Stereoelectronic Effects in the Hydrogenolysis and Birch Reduction of Some Hindered Tertiary-Benzylic Carbinols
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3-(4'-Methoxyphenyl)pentan-3-ol (3a) and 3-(4'-methoxyphenyl)-2,4-dimethylpentan-3-ol (3b) underwent catalytic hydrogenolysis over 10percent palladium/charcoal at moderate temperatures and pressures.The more hindered tertiary-benzylic carbinols 3-(4'-methoxyphenyl)-2,2,4-trimethylpentan-3-ol (6), 3-(4'-methoxyphenyl)-2,2,4,4-tetramethylpentan-3-ol (3c), 1-(4'-methoxyphenyl)-2,2,6,6-tetramethylcyclohexan-1-ol (8) and 1-(1',1'-dimethylethyl)-6-methoxy-2,2-dimethyl-1,2,3,4-tetrahydronaphthalen-1-ol (10) were completely resistant to hydrogenolysis, even under vigorous conditions.While the hindered tertiary-benzylic carbinols (6), (8) and (10) readily underwent Birch reduction, the analogous di-t-butyl anisyl carbinol (3c) was unchanged.The failure of (3c) to undergo Birch reduction is probably due to a hitherto unrecognized stereoelectronic effect: the C-OH bond of (3c) is constrained to lie more or less in the plane of the benzene ring, and addition of an electron to the benzene ring of the derived oxyanion (31) is inhibited in this conformation.
- Collins, David J.,Jacobs, Howard A.
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p. 1989 - 2004
(2007/10/02)
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- Thermolabile Hydrocarbons, XX. Synthesis, Structure, and Strain of Sym. Tetraalkyl-1,2-diarylethanes
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The syntheses of 18 1,1,2,2-tetraalkyl-1,2-diarylethanes 1 - 4 by dimerisation procedures starting with 10 - 13 are reported.In the absence of p-substituents X and with increasing alkyl side chains the α,p-dimers 6 or their aromatic counter parts 7 are obtained besides or instead of 1.The relationships between strain enthalpy Hs, bond lengths, bond angles, torsional angles, and rotational barrier are discussed on the basis of force field calculations.They are supported by two additional experimental structure determinations by X-ray diffraction.
- Kratt, Guenter,Beckhaus, Hans-Dieter,Lindner, Hans Joerg,Ruechardt, Christoph
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p. 3235 - 3263
(2007/10/02)
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- Antiestrogens. Synthesis and Evaluation of Mammary Tumor Inhibiting Activity of 1,1,2,2-Tetraalkyl-1,2-diphenylethanes
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Among the newly synthesized 1,1,2,2-tetraalkyl-1,2-diphenylethanes, 1,1,2,2-tetramethyl-1,2-bis(4'-hydroxyphenyl)ethane (23) and 1,1,2,2-tetramethyl-1,2-bis(3'-hydroxyphenyl)ethane (26) were the most active compounds regarding estradiol receptor affinity, exhibiting Ka values of 0.73*108 and 0.67*108 M-1, respectively.In vivo, 23 and 26 showed only very small uterotrophic activity in the mouse.They strongly inhibited (73percent) the estrone-stimulated mouse uterine growth.Tested on the 9,10-dimethyl-1,2-benzanthracene induced hormone-dependent mammary adenocarcinoma of the Sprague-Dawley rat, compounds 23 and 26 exhibited a dose-dependent inhibition of the tumor growth, having a strong effect at a dose of 20 (mg/kg)/day (compound 23).
- Hartmann, Rolf W.,Kranzfelder, Gerhard,Angerer, Erwin, v.,Schoenenberger, Helmut
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p. 841 - 848
(2007/10/02)
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