Studies of nitriles. XI. Preparation and chemistry of Schiff bases of ADAN, 2-amino-3,3-dichloroacrylonitrile. A highly effective conversion into 2-substituted-4(5)-chloroimidazole-5(4)-carbaldehydes.

Abstract

Schiff bases of 2-amino-3, 3-dichloroacrylonitrile (ADAN) have been prepared in excellent yields by condensation of ADAN with various aldehydes under mild conditions. These Schiff bases (2, 3, 4) are highly reactive polyfunctional compounds and useful synthetic intermediates : the chlorine atoms of Schiff base 2e react with various nucleophiles such as alkoxides, mercaptides, and primary and secondary amines giving the corresponding 3, 3-dialkoxy-, 3, 3-bis (substituted mercapto)-, and 3, 3-bis (substituted amino)-derivatives (7, 8, and 10), respectively. Reduction of Schiff base 2e with zinc powder under mild conditions resulted in formation of the monochloro derivative 5. With anhydrous hydrogen chloride in ether, these Schiff bases underwent smooth cyclization to new 4 (5)-chloro-5(4)-dichloromethylimidazoles 11, which in turn were converted into 4 (5)-chloro-imidazole-5 (4)-carbaldehydes 12 in excellent yields upon hydrolysis.