- Fast halogenation of some N-heterocycles by means of N,N'-dihalo-5,5- dimethylhydantoin
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An instantaneous, selective and high-yielding halogenation process is reported. The method operates with imidazoles, pyrazoles, and indoles under benign reaction conditions. The developed process involves the use of N,N'-dihalo-5,5-dimethylhydantoins (halo=chlorine, bromine, iodine) as halogenation reagents that are activated by catalytic quantities of a strong Bronsted acid. Moreover, the halogenation process is switchable to produce either the mono- or di-halogenated products. Issues related to the reaction mechanism are investigated and a proposal for a reaction mechanism is disclosed.
- Sandtorv, Alexander H.,Bjorsvik, Hans-Rene
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p. 499 - 507
(2013/05/08)
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- Syntheses of (trifluoromethyl)imidazoles with additional electronegative substituents, an approach to receptor-activated affinity labels
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Electrophilic substitution in 2- and 4-(trifluoromethyl)imidazoles provides derivatives containing one or two nitro, chloro, bromo, or iodo groups. Fluoro and chloro derivatives were also prepared by photochemical trifluoromethylation of the respective haloimidazole. The results demonstrate that (trifluoromethyl)imidazoles behave fairly typically under the conditions of electrophilic nitration and halogenation. Of the alternative routes to the desired bifunctional and trifunctional imidazoles, electrophilic substitution on the preformed (trifluoromethyl)imidazole appears to be the method of choice in most cases. A large number of the products show herbicidal or insecticidal activity.
- Hayakawa, Yoshio,Kimoto, Hiroshi,Cohen, Louis A.,Kirk, Kenneth L.
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p. 9448 - 9454
(2007/10/03)
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- 4,5-Dichloroimidazole-2-carboxylic acid derivatives
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4,5-Dichloroimidazole-2-carboxylic acid derivatives of the formula STR1 in which the group STR2 represents a carbon atom which has three bonds to hetero-atoms, and their salts with bases, possess insecticidal, acaricidal, fungicidal, nematicidal and herbicidal properties.
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