- Regioselective halogen-metal exchange reaction of 3-substituted 1,2-dibromo arenes: The synthesis of 2-substituted 5-bromobenzoic acids
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Regioselective halogen-metal exchange reactions using isopropylmagnesium chloride were carried out on 3-substituted 1,2-dibromo arenes. Eleven examples are given. Georg Thieme Verlag Stuttgart.
- Menzel, Karsten,Dimichele, Lisa,Mills, Paul,Frantz, Doug E.,Nelson, Todd D.,Kress, Michael H.
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p. 1948 - 1952
(2008/02/08)
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- Halogen-metal exchange of 3-substituted 1,2-dibromoarenes: The use of long-range JCH coupling constants to determine regiochemistry
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Regioselective halogen/metal exchange reactions were carried out on a series of 3-substituted-1,2-dibromoarenes. Product mixtures were quenched with CO2 to form the corresponding benzoic acid analogs to facilitate HPLC and NMR analysis. Substitution at the 3-position could readily be assigned on the basis of 2D HMBC long-range correlations, while assignment at the 2-position was not as straightforward. The use of three-bond JCH coupling constant measurements, extracted from 1-D 1H coupled 13C experiments, were necessary to render unequivocal regio assignments. Copyright
- DiMichele, Lisa,Menzel, Karsten,Mills, Paul,Frantz, Doug,Nelson, Todd
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p. 1041 - 1043
(2008/02/05)
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- Ortho-metalation of unprotected 3-bromo and 3-chlorobenzoic acids with hindered lithium dialkylamides
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Upon treatment of 3-chloro/bromobenzoic acids with hindered lithium dialkylamides (LDA or LTMP) at -50 °C, lithium 3-chloro/bromo-2-lithiobenzoates are generated. These dianions can be trapped as such to afford after electrophilic quenching a variety of s
- Gohier, Frederic,Mortier, Jacques
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p. 2030 - 2033
(2007/10/03)
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- Substitution Reactions of Phenylated Aza-Heterocycles. Part 2. Bromination of Some 2,5-Diaryl-1,3,4-oxadiazoles
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Electrophilic bromination of the title compounds may be achieved using either bromine in oleum, or bromine and potassium bromate in a sulphuric-acetic acid mixture.Under the milder reaction conditions provided by the latter, 2-(p-nitrophenyl)-5-phenyl-1,3,4-oxadiazole (2), the model compound used in this study, is mono- and di-brominated in the phenyl ring.In the first bromination step, all three monobromo-isomers are produced in appreciable amount.The orientation of the second bromination is controlled entirely by the first bromine and not by the oxadiazole substituent: this is confirmed by a separate study of the bromination of the three monobromo-compounds (3a-3c).
- Blackhall, Alexander,Brydon, Donald L.,Javaid, Khalid,Sagar, Anthony J. G.,Smith, David M.
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p. 3485 - 3497
(2007/10/02)
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