Reaction of N ‐(phenyl and methyl)‐ C ‐arylnitrones with DMAD in ionic liquid: Efficient synthesis of Δ 4 ‐isoxazolines

Facile synthesis of N ‐(methyl and phenyl)‐Δ 4 ‐isoxazolines via the reaction of (Z)‐ N ‐(methyl and phenyl)‐ C ‐arylnitrones with dimethyl acethylenedicarboxylate, DMAD, in ionic liquid is described. (Z)‐ N ‐methyl‐ C ‐arylnitrones afforded the high yield of N ‐methyl‐Δ 4 ‐isoxazolines 4a , 4b , 4c , 4d , 4e in ionic liquid, [bmim]BF 4 , at room temperature. However, the reaction of (Z)‐ N ‐phenyl‐ C ‐arylnitrones with DMAD afforded the mixtures of cis and trans isomers of related N ‐phenyl‐Δ 4 ‐isoxazolines ( 5a , 5b , 5c , 5d , 5e , 5f , 5g , 5h , 5i , 5j , 6a , 6b , 6c , 6d , 6e , 6f , 6g , 6h , 6i , 6j ) under these conditions. J. Heterocyclic Chem., (2012).