The study of the interaction of 2-chloro- and 2,3-dichloro-5(8)-RO-1,4-naphtoquinones with CH-acids

Abstract

The regioselectivity of the reaction of 2-chloro- and 2,3-dichloro-5-substituted naphthoquinones with CH-acids is studied. It is shown that the nature of the substituent in 5-RO-1,4-naphthoquinones plays the main role in the predominant formation of one of the possible regioisomers in the reactions of nucleophilic substitution. It is substantiated that the orientation of the nucleophilic attack by CH-acid on the C3 atom of 5-RO-1,4-naphthoquinones is due to the fact that the 5-methoxy and 5-acetoxy groups have a passivating effect on the electron-accepting properties of the C4=O group due to the positive conjugation effect. As a result, the electrophilic center appears in position 3. It is established that the interaction of 2- or 3-chloro-substituted 5-RO-1,4-naphthoquinones with CH-acids proceeds with the formation of 2- and 3-addition products with a preference for products of substitution of the chlorine atom in 3rd position. The structure of the regioisomers is confirmed by spectral data and by countersynthesis.