3-COMPONENT CYCLOCONDENSATIONS, - 2 METHODS FOR THE EFFICIENT PREPARATION OF 5-AMINOTHIAZOLIUM SALTS VIA THE REACTION OF ISOCYANIDES EITHERWITH DIMETHYLTHIOFORMAMIDE AND IMINO CHLORO SULFIDES OR BENZALDIMINESAND ARYL CHLOROTHIOFORMATES

Treatment of imino chloro sulfides with dimethylthioformamide and isoc yanides at room temperature provides selectively the 5-amino-4-(dimeth ylamino)-2-(methylthio)(or phenylthio)thiazolium salts. Similarly, the reactions of p-tolyl chlorothionoformate and phenyl chlorodithioforma te with a mixture of benzaldimine and isocyanide afford rapidly the 5- amino-4-phenylthiazolium salts. We suggest that these reactions involv e the N-(thiocarbonyl)formamidinium and benzylideniminium chlorides as transient intermediates, which are trapped by isocyanides according t o a [1 + 4] cycloaddition process. The structure of the thiazolium sal ts and some of their reactivities are discussed.