Picryl and 4-cyano-2,6-dinitrophenyl derivatives of acetoacetate esters

Abstract

The compounds described in the literature as ethyl 2-picryl-3-oxobutanoate (1) and ethyl 2,2-dipicryl-3-oxobutanoate (2) formed by the action of picryl chloride on ethyl acetoacetate in the presence of base are in fact ethyl 3-hydroxy-2-picrylbut-2-enoate (3a) and ethyl 2-picryl-3-picryloxybut-2-enoate (4a) respectively. A number of analogues of (3a) and (4a), in which picryl moieties have been replaced by the group 4-cyano-2,6-dinitrophenyl, have been synthesised. These compounds have enabled ¹H n.m.r. assignments to be made unambiguously.