Enamine chemistry. Part III. Reaction of αβ-unsaturated acid chlorides with enamines of acyclic ketones. Preparation of cyclohexane-1,3-diones

Abstract

Reaction of acryloyl, crotonoyl, and methacryloyl chlorides with the morpholine enamine of diethyl ketone has been shown to give 2,4-dimethyl-, 2,4,5-trimethyl-, and 2,4,6-trimethyl-cyclohexane-1,3-diones respectively. The intermediate substituted 3-morpholinocyclohex-2-enones have been isolated and characterised as their perchlorates. Acryloyl chloride and the morpholine enamine of ethyl isopropyl ketone and the dimethylamine enamine of di-isopropyl ketone gave 2,2,4-trimethyl- and 2,2,4,4-tetramethyl-cyclohexane-1,3-diones respectively. The morpholine enamine of dibenzyl ketone gave 3-morpholino-2,4-diphenyl-cyclohex-2-enone which could not be hydrolysed to the cyclohexane-1,3-dione. The mechanism of the reaction is discussed.