Reduction of enaminones in the preparation of 3-aminocyclohexanols; a novel preparation of tetronic acid

Abstract

Reduction of enaminones derived from cyclohexane-1,3-dione gives the corresponding 3-aminocyclohexanols. In the case of the N-unsubstituted derivative the major product is the trans-isomer. The position of attack of ammonia on 2-acetylcyclopentanone and 2-acetylcyclohexanone has been elucidated by reduction of the derived enaminones. In the former case the base attacks the side-chain carbonyl group, but in the latter the ring carbonyl group. Reduction of 2-(substituted amino)fumaric esters gave enaminone analogues of tetronic acid, hydrolysis of which afforded tetronic acid [4-hydroxyfuran-2(5H)-one] itself.