Reaction of N‐(phenyl and methyl)‐C‐arylnitrones with DMAD in ionic liquid: Efficient synthesis of Δ⁴‐isoxazolines

Abstract

Facile synthesis of N‐(methyl and phenyl)‐Δ4‐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‐Δ4‐isoxazolines 4a, 4b, 4c, 4d, 4e in ionic liquid, [bmim]BF4, 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‐Δ4‐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).

[Bmim]BF4: A Versatile Ionic Liquid for the Synthesis of Diverse Bioactive Heterocycles

“…After completion of the reaction ionic liquid was recovered, and reused several times for the same batch of reaction. Later on, the same group also synthesized N ‐(methyl/phenyl)‐Δ 4 ‐isoxazolines ( 69 ) by the reaction of ( Z )‐ N ‐(methyl/phenyl)‐ C ‐arylnitrones ( 68 ) and dimethyl acethylenedicarboxylate ( 3 a ) in the same ionic liquid [bmim]BF 4 at room temperature (Table ) …”