Convenient and Improved Halogenation of 3,5-Diarylisoxazoles Using N-Halosuccinimides

Abstract

The convenient C-4 halogenation of 3,5-diarylisoxazoles using N-halosuccinimides (NBS, NCS, or NIS) in acetic acid is described. A strong acid catalyst was required for efficient halogenation of some isoxazoles depending on the substituent on the 5-phenyl ring. Finally, the 4-iodoisoxazoles were found to undergo a novel proto-deiodination upon heating in the presence of H₂SO₄.

Key words

isoxazoles - halogenation - N-halosuccinimides - iodo cleavage - solvent effects

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23

A volatile pink color developed during the deiodinations which is presumed to be iodine acetate.