Three-Component Cyclocondensations. Two Methods for the Efficient Preparation of 5-Aminothiazolium Salts via the Reaction of Isocyanides Either with Dimethylthioformamide and Imino Chloro Sulfides or Benyaldimines and Aryl Chlorothioformates

Article abstract of DOI:10.1021/jo00074a032

Treatment of imino chloro sulfides with dimethylthioformamide and isocyanides at room temperature provides selectively the 5-amino-4-(dimethylamino)-2-(methylthio) (or phenylthio)thiazolium salts.Similarly, the reactions of p-tolyl chlorothionoformate and phenyl chlorodithioformate with a mixture of benzaldimine and isocyanide afford rapidly the 5-amino-4-phenylthiazolium salts.We suggest that these reactions involve the N-(thiocarbonyl)formamidinium and benzylideniminium chlorides as transient intermediates, which are trapped by isocyanides according to a <1 + 4> cycloaddition process.The structure of the thiazolium salts and some of their reactivities are discussed.