Regioselectivity of the SEAr reaction of 8-chloro-3,4-dihydro-1H-[1,4]oxazino[4,3-a]benzimidazole

The article investigates the impact of process temperature and electrophilic agent addition time on the regioselectivity of the SEAr reaction. The purpose is an efficient functionalisation of the bifarmacophore molecule 8-chloro-3,4-dihydro-1H-[1,4]oxazino[4,3-a]benzimidazole in electrophilic nitration and halogenation reactions. Two isomeric 7- and 9-substituted products were formed during these reactions. A larger amount of 7-R-8-chloro-3,4-dihydro-1H-[1,4]oxazino[4,3-a]benzimidazole was formed. Reducing the reaction temperature and the concentration of the electrophilic agent in the reaction mixture increased the selectivity of the process for forming the isomer.