- Singlet vs Triplet Reactivity of Photogenerated α,n-Didehydrotoluenes
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The reactivity of α,n-didehydrotoluenes (DHTs) in protic media (organic/aqueous mixtures) was explored by means of a combined computational and experimental approach. These intermediates were generated via a photoinduced double elimination process occurring in (chlorobenzyl)trimethylsilanes and led to the formation of a varied products distribution, depending on the isomer tested. Irradiation of ortho- and para-derivatives resulted, respectively, in the formation of triplet α,2- and α,4-DHTs, whose diradical reactivity led to both radical and polar products. On the other hand, irradiation of the meta-precursor led to the singlet α,3-DHT isomer. The latter showed a marked preference for the formation of polar products and this was rationalized, as supported by computational evidence, via the involvement of a zwitterionic species arising through interaction of the nucleophilic solvent with the benzylic position of the DHT.
- Pedroli, Chiara,Ravelli, Davide,Protti, Stefano,Albini, Angelo,Fagnoni, Maurizio
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p. 6592 - 6603
(2017/07/15)
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- A convenient synthesis of (Z)-1-chloro-1-alkenes and (Z)-1-chloro-2-alkoxy-1-alkenes
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Mild, room temperature CrCl2 reduction of 1,1,1-trichloroalkanes stereoselectively generates (Z)-1-chloro-2-substituted-1-alkenes in excellent yields.
- Baati, Rachid,Barma,Krishna, U.Murali,Mioskowski, Charles,Falck
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p. 959 - 961
(2007/10/03)
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- Use of Sacrificial Anodes in Electrochemical Functionalization of Organic Halides
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This article reviews the new possibilities in organic synthesis offered by the electroreduction of organic halides in the presence of various electrophiles using sacrificial metallic anodes.
- Chaussard, Jacques,Folest, Jean-Claude,Nedelec, Jean-Yves,Perichon, Jacques,Sibille, Soline,Troupel, Michel
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p. 369 - 381
(2007/10/02)
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- ABSOLUTE RATES AND SELECTIVITY OF HOMOLYTIC SUBSTITUTION AT A CARBON ATOM IN BENZYL COMPLEXES OF COBALT. EFFECT OF AXIAL LIGANDS
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The absolute rate constants were determined for the bimolecular homolytic substitution of organocobalt groups by a trichloromethyl radical in the benzylglyoxime complexes of cobalt, and the effect of axial and equatorial ligands on the reaction rate was studied.The change in the dissociation energy of the cobalt-carbon bond has a determining effect on the substitution rate.The relation between the reactivity and selectivity with variation of the axial ligand is inverse in nature.
- Dneprovskii, A. S.,Kondakov, D. Yu.,Kasatochkin, A. N.
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- EFFECT OF STRUCTURAL FACTORS ON RATE OF BIMOLECULAR HOMOLYTIC SUBSTITUTION AT A CARBON ATOM IN BENZYL COMPLEXES OF COBALT
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The reaction of the benzylglyoximate complexes of cobalt with bromotrichloromethane leads to the formation of 1,1,1-trichloro-2-arylethanes, which correspond to bimolecular homolytic substitution of the cobalt-containing group by the trichloromethyl radic
- Dneprovskii, A. S.,Kasatochkin, A. N.,Kondakov, D. Yu.
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p. 833 - 838
(2007/10/02)
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- Electrochemical Cross-Coupling of Alkyl Halides in the Presence of a Sacrificial Anode
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The electrochemical trichloromethylation of various alkyl halides has been obtained in high yields in an undivided cell in the presence of a sacrificial anode.This cross-coupling process has been extended to the preparation of numerous gem-dichloro compounds from trichloro-substituted methanes and alkyl halides.Zinc,magnesium or aluminium were used as anodes according to the reduction potentiel of the reagents.Mixtures of polar aprotic solvents,e.g.THF-TMU or THF-NMP, were found more appropriate than pure solvents.The critical role of the metallic ions from the consumption of the anode has been clearly evidenced.
- Nedelec, Jean-Yves,Mouloud, Hassan Ait Haddou,Folest, Jean-Claude,Perichon, Jacques
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p. 4720 - 4724
(2007/10/02)
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- ELECTROCHEMICAL CROSS-COUPLING OF ORGANIC HALIDES: TRICHLORMETHYLATION AND RELATED SYNTHESIS OF GEM-DICHLORO COMPOUNDS
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The cross-coupling of activated alkyl halides with carbon tetrachloride or substituted trichloromethanes can be obtained electrochemically in good yield in an undivided cell with a sacrificial anode.
- Nedelec, J. Y.,Ait-Haddou-Mouloud, H.,Folest, J. C.,Perichon, J.
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p. 1699 - 1700
(2007/10/02)
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- HOMOLYTIC DISPLACEMENT AT CARBON VI. SYNTHESIS OF TRICHLOROETHYLARENES FROM BENZYLCOBALOXIMES
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Benzylbis(dimethylglyoximato)pyridinecobalt(III) reacts with bromotrichloromethane at from 50 to 90 deg C in chloroform to give good yields of trichloroethylbenzene, which are higher when imidazole is present in the reaction mixture.Methyl- and polymethyl-substituted benzylbis(dimethylglyximato)pyridinecobalt(III) complexes give higher yields of the corresponding trichloroethylarenes (85-90percent), whereas 4-chlorobenzylbis(dimethylglyoximato)pyridinecobalt(III) only gives the 4-nitro-trichloroethylarene when imidazole is present during the reaciton.Similar reactions were observed with benzylcobaloximes and trichloromethanesulphonyl chloride both thermally and under irradiation by tungsten lamps through all-pyrex apparatus.The reactions are interpreted as a direct attack of the trichloromethyl radical on the α-carbon of the benzyl ligand.
- Bougeard, Peter,Gupta, B. Dass,Johnson, Michael D.
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p. 211 - 219
(2007/10/02)
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