RESUMO
A protocol for the N-bromosuccinimide (NBS)- and trichloroisocyanuric acid (TCCA)-mediated synthesis of novel 2-halomethylene-3-oxoketoximes via one-pot halogenation/oxidation of isoxazoline N-oxide derivatives is described here. The keto functionality of 3-ketoximes was selectively reduced by lithiumaluminum hydride to synthesize an unprecedented type of Baylis-Hillman oxime, which underwent N-O coupling to produce new isoxazoline N-oxide derivative.
Assuntos
Benzofenonas/síntese química , Halogênios/química , Isoxazóis/química , Óxidos/química , Oximas/síntese química , Benzofenonas/química , Cristalografia por Raios X , Íons/química , Modelos Moleculares , Estrutura Molecular , Oximas/químicaRESUMO
The unusual alcohol mediated formation of 4-oxo-2-aryl-4H-chromene-3-carboxylate (flavone-3-carboxylate) derivatives from 4-hydroxycoumarins and ß-nitroalkenes in an alcoholic medium is described. The transformation occurs via the in situ formation of a Michael adduct, followed by the alkoxide ion mediated rearrangement of the intermediate. The effect of the different alcohol and nonalcohol media on the reaction was investigated.
Assuntos
4-Hidroxicumarinas/química , Álcoois/química , Benzopiranos/síntese química , Benzopiranos/química , Cristalografia por Raios X , Modelos Moleculares , Estrutura MolecularRESUMO
An HTIB mediated oxidative N-O coupling strategy for the synthesis of some isoxazoline N-oxide derivatives from ß-hydroxyketoximes is described, along with a comparative study of the efficiency of N-O coupling in two different solvents. A plausible mechanism for the conversion is proposed.