Amination azinones

A bifunctional autocatalytic effect of azinones in general is possible in certain nucleophilic reactions such as amination. Zollinger has found that 2-pyridone is the best catalyst for anilino-dechlorination of various chloroazines. It seems likely that examples of autocatalysis will be found when the substrate contains an azinone moiety. The azinone hy-products of displacement reactions may also function in this way as catalysts for the main reaction. 

Acylations of anions formed by deprotonation of azinones are not described in previous editions <1984CHEG(2)1, 1996CHEC-II(6)1>. 4,5-Dichloropyridazin-3(2//)-one is smoothly acylated at N-2 with acyl chlorides in the presence of triethylamine in dichloromethane at room temperature, —10 or —22°C <2002S733>. The resulting compounds have been used as mild acylating reagents for amines (see Section 8.01.8.4). 

POCI3 chlorinations (Eq. (8)) are acid-catalyzed reactions of such reaction products]. The hydrogen bonding of azinones is related to that of iV-oxides, discussed below, and to that of ketones (with water and alcohols) and has been demonstrated by infrared measurements on pjn-idinethione in alcohols and by the electronic absorption spectra of azinones in water. 6-Chloro-l,3-dimethyl-pyrimidine-2,4-dione is rapidly aminated at 20° (with heat evolution) by methyl- or ethyl-amines, etc., in protic media (water or alcohols). 

Of comparable origin is the reactivity of 5-chloro-2,6-dimethyl- and 5-chloro-l,6-dialkyl-pyridazin-3-ones with ammonia, amines, aJkoxides, and cyanide ion. The exact relation of the reactivity of these azinones to the corresponding parent compound is not clear without a direct qualitative comparison or kinetic data. 

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