- Transitional-Metal-Activated Organic Compounds, XXXV. - ortho-Alkylation of Aromatic Azo Compounds with Alkyllithium Reagents and Lithium Trimethylferrate(1-)
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Whereas methyllithium reacts with 4-(dimethylamino)-, 4-amino-, and 4-methoxyazobenzene, respectively, by ortho-methylation of the electron-rich phenyl residue of the azo compound, (CH3)3FeLi ortho-methylates the less electron-rich phenyl group of 4-(dimethylamino)azobenzene.A mechanistic rationalization is given for both reaction modes.Key Words: Lithium, organo compounds / Iron, organo compounds / Azo compounds / ortho-Alkylation
- Kauffmann, Thomas,Jordan, Jan,Sander, Joerg
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p. 153 - 155
(2007/10/02)
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- Sterically Hindered Azobenzenes: Isolation of Cis Isomers and Kinetics of Thermal Cis --> Trans Isomerization
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A series of highly hindered ortho-alkylated azobenzenes has been isolated in the cis configuration for the first time.The crystal structure of one of these compounds, cis-2,2',6,6'-tetraisopropylazobenzene, shows that the molecule accommodates the bulky s
- Bunce, Nigel J.,Ferguson, George,Forber, Christine L.,Stachnyk, Greg J.
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p. 394 - 398
(2007/10/02)
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- Liquid Crystalline Solvents as Mechanistic Probes. 11. The Syn -> Anti Thermal Isomerization Mechanism of Some Low-"Bipolarity" Azobenzenes
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The effects of solvent order on the syn -> anti isomerization rates of 15 azobenzenes have been investigated.The activation parameters determined in a cholesteric phase consisting of a 35/65 (w/w) mixture of cholesteryl chloride/cholesteryl nonanoate and in several other solvents are more consistent with an isomerization mechanism which proceeds via inversion (in plane) rather than rotation (out of plane).A correction of our previously reported data is given.The anomalous behavior of the isomerization mechanism of di-ortho-methylated azobenzenes is demonstrated by means of isokinetic plots.
- Otruba, Joseph P.,Weiss, Richard G.
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p. 3448 - 3453
(2007/10/02)
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