Access to 3-arylmethyl-5-(methylthio)isoxazoles via an initial ring-opening of 2-methylthio-4-nitrothiophene

The reactions of 1,1-bis(methylthio)-3-nitro-4-pyrrolidino-1,3-butadiene (deriving from the initial ring-opening of 2-methylthio-4-nitrothiophene with pyrrolidine and silver nitrate in EtOH) with arylmagnesium bromides result in the chemoselective replacement of the pyrrolidino group with the aryl moiety of the Grignards. The 4-aryl-1,1-bis(methylthio)-3-nitro-1,3-butadienes thus obtained are the key intermediates for the effective synthesis, through the corresponding reduction products 4-aryl-3-hydroximino-1,1-bis(methylthio)-1-butenes, of the previously unknown 3-arylmethyl-5-(methylthio)isoxazoles.