Iron-catalyzed direct sulfenylation and selenylations of phenylpyrazoles: Synthesis of fipronil derivatives with disulfides promoted by a catalytic amount of iodine

Article abstract of DOI:10.1080/00397911.2011.584262

The direct thiolation of phenylpyrazole with disulfide using the FeBr ₃/I₂ complex as the catalyst in MeCN at 80 °C was reported. With the optimum conditions, several fipronil derivatives of 4-sulfenylpyrazole were synthesized by the reaction of 5-amino-1-[2,6-dichloro- 4-(trifluoromethyl)phenyl-lH-pyrazole-3-arbonitrile (1a) with disulfides (2) in moderate to good yields. The coupling reaction with diaryl diselane also occurred under similar conditions.