Halogenation of N′-(Arenesulfonyl)-N-[2,6(3,5)-dialkyl-4-oxocyclohexa-2,5-dien-1-ylidene]benzenecarboximidamides and Their Reduction Products

Abstract

Halogenation of N′-(arenesulfonyl)-N-[2,6(3,5)-dialkyl-4-oxocyclohexa-2,5-dien-1-ylidene]benzenecarboximidamides and their reduction products gave derivatives containing up to four halogen atoms. The degree of halogenation can be controlled by variation of the reaction conditions only in the reactions with 2,6(3,5)dimethyl derivatives. The maximum number of halogen atoms were introduced into 2,6(3,5)-dimethyl- and 3,5-diisopropyl-substituted substrates. The presence of bulky tert-butyl groups in the quinoid ring significantly reduced the degree of halogenation, and halogen molecule added to only one C=C double bond of the quinoid ring. The axial orientation of alkyl substituents in the cyclohexene products suggests syn addition of halogens to the C=C double bond of the quinoid ring.