4-(5-Benzyl-3-((4-fluorophenyl)sulfonyl)-5-methyl-4,5-dihydrofuran-2-yl)-2-nitrobenzamide

As part of our ongoing attempt to broaden the applications of the amidoxime moiety as a potential source of new antileishmanial agents, this study focuses on the product 4-(5-Benzyl-3-((4-fluorophenyl)sulfonyl)-5-methyl-4,5-dihydrofuran-2-yl)-2-nitrobenzamide. This unexpected amide was obtained in an 85% yield as the major product with a conventional amidoxime synthesis protocol (Ethanol/Na2CO3) involving the reaction of hydroxylamine and a nitrile group. The formation of this amide derivative instead of the expected amidoxime can be attributed to two complementary effects: the strong electron effect of the nitro group and the influence of ethanol, a polar protic solvent. Alternatively, the desired amidoxime derivative, 4-(5-benzyl-3-((4-fluorophenyl)sulfonyl)-5-methyl-4,5-dihydrofuran-2-yl)-N′-hydroxy-2-nitrobenzimidamide, was obtained in an 80% yield by an alternative protocol (DMSO/KOtBu). This original compound, featuring a nitro group in the ortho position to the amidoxime, will be further evaluated, both in the field of medicinal chemistry and in other relevant areas, highlighting an unusual method to access amidoximes from hindered substrates.