Studies of Nitriles. VIII. Reactions of N-Acyl Derivatives of 2-Amino-3, 3-dichloroacrylonitrile (ADAN) with Amines. (1). A New Synthesis of 2-Substituted-5-(substituted amino) oxazole-4-carbonitriles and-4-N-acylcarboxamides

抄録

2-Acetylamino-3, 3-dichloroacrylonitrile (1a) reacted with 2 molar eq. of mercaptides and alkoxides to yield 2-acetylamino-3, 3-bis-(substituted mercapto) acrylonitriles (2) and 2-acetylamino-3, 3, 3-trialkoxypropionitriles (4), respectively, in high yields. In contrast to these results, we found that the reaction of 1a with various aliphatic primary and secondary amines including ammonia and hydrazine gave 2-methyl-5-(substituted amino) oxazole-4-carbonitriles (6) in almost quantitative yields under mild conditions. Reaction of 1a with bifunctional amines such as ethylenediamine and aminoethanethiol generated other types of cyclization products, e.g., imidazolidine and thiazolidine derivatives (8a, b), as major products. Treating 1 or 2-amino-3, 3-dichloroacrylonitrile (ADAN) with various acid anhydrides in the presence of conc. sulfuric acid catalyst resulted in a new one-step synthesis of imidic compounds, 2-acylamino-3, 3-dihalogeno-N-acylacrylamides (21). The reaction of 21 with aliphatic secondary amines yielded 2-substituted-5-(substituted amino) oxazole-4-N-acylcarboxamides (32). The mechanism of the cyclization to oxazoles and the formation of imidic compounds are discussed.