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Halogenation O 0235Amidines as Potent Nucleophilic Organocatalysts for the Transfer of Electrophilic Bromine from N-Bromosuccinimide to Alkenes. -Racemic iso-amarine (IAM) is described as a potent organo catalyst for both the bromoacetoxylation of alkenes and bromolaconization. An asymmetric version using the enantiopure (R,R)-catalyst is investigated; however, only racemic products are obtained. -(AHMAD, S. M.; BRADDOCK*, D. C.; CANSELL, G.; HERMITAGE, S. A.; REDMOND, J. M.; WHITE, A. J. P.; Tetrahedron Lett. 48 (2007) 34, 5948-5952; Dep. Chem., Imp. Coll., London SW7 2AZ, UK; Eng.) -Mais 49-032

Halogenation O 0235Dimethylformamide, Dimethylacetamide and Tetramethylguanidine as Nucleophilic Organocatalysts for the Transfer of Electrophilic Bromine from N-Bromosuccinimide to Alkenes. -The nitrogen compounds are found to be suitable catalysts for the bromolactonization of ω-unsaturated carboxylic acids with NBS. The most active agent tetramethylguanidine also promotes the bromoacetoxylation of alkenes with NBS and acetic acid. -(AHMAD, S. M.; BRADDOCK*, D. C.; CANSELL, G.; HERMITAGE, S. A.; Tetrahedron Lett. 48 (2007) 6, 915-918; Dep. Chem., Imp. Coll., London SW7 2AZ, UK; Eng.) -Mais 19-034