Aromatic substitution. Part XXIV. The Emmert reaction: effects of substituents on orientation

Abstract

The reactions of pyridine and 3-picoline with cyclohexanone and 2-methylcyclohexanone, and of pyridine with 4-t-butylcyclohexanone, in the presence of magnesium amalgam have been studied quantitatively. In the latter case the conformations of the products have been established. The cis--trans-isomer ratio was 54·2:45·8. With 3-picoline, attack took place predominantly at C-6. The results are thought to fit a 1,3-dipolar cycloaddition or a co-ordination of R₂[graphic omitted]·O[graphic omitted] at nitrogen followed by nucleophilic cyclisation mechanism.