Reaction of ketenes with <i>N,N</i>‐Disubstituted 2‐Aminomethylenecycloalkanones III. Synthesis of <i>N,N</i>‐Disubstituted 3,3‐Diehloro‐4‐amino‐5,6‐polymethylene‐3,4‐dihydro‐α‐pyrones

Abstract

Abstract The reaction of dichloroketene with N,N ‐Disubstituted 2‐aminomethylenecyclopentanones, cyclohexanones, cycloheptanones and cyclooctanones gave the 1,4‐cycloadducts, namely N,N ‐Disubstituted 3,3‐dichloro‐4‐amino‐5,6‐polymethylene‐3,4‐dihydro‐α‐pyrones. The structures of these products were determined by uv, ir and nmr spectral data, as well as by dehydrochlorination of the adduct, 3,3‐dichloro‐4‐diphenylamino‐5,6‐tetramethylene‐3,4‐dihydro‐α‐pyrone, which led to 3‐chloro‐4‐diphenylamino‐5,6‐tetramethylene‐α‐pyrone. The by‐product of the cycloaddition reaction was the N,N ‐Disubstituted dichloroacetamide, the formation of which varies according to the substituents on the nitrogen atom.