1968 Volume 41 Issue 12 Pages 2954-2959
Thiophenc-2-carbonitrile N-oxide (I) and 5-chlorothiophene-2-carbonitrile N-oxide (II) were synthesized by the chlorination of corresponding aldoxime with nitrosyl chloride. These compounds gave Δ2-isoxazolines and isoxazoles through 1,3-dipolar cycloaddition reaction with compounds having double or triple bond as dipolarophiles. In the cycloaddition reaction, II was less reactive than I. This would be explained by stability of II owing to electron-withdrawing ability of chlorine atom at 5-position in the thiophene ring. Furoxans, the dimers of the nitrile N-oxide, were formed from these 1,3-dipoles in the absence of dipolarophile.
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