Substituent effects on stereoselectivity of dihalocarbene reactions with cyclohexadiene and on the reactivity of bis-dihalocyclopropanes in electrophilic nitrations en route to pyrimidine N-oxides.
Kseniya N SedenkovaElena B AverinaYuri K GrishinJulia V KolodyazhnayaVictor B RybakovTamara S KuznetsovaAudrey HughesGabriel Dos Passos GomesIgor V AlabuginNikolay S ZefirovPublished in: Organic & biomolecular chemistry (2018)
Tricyclic bis-adducts of cyclohexa-1,4-diene with bromofluorocarbene and non-symmetric adducts with both bromofluoro- and dichlorocarbenes were synthesised selectively. The treatment of the bis-adducts with nitrating reagents in acetonitrile affords the products of heterocyclization of a sole dihalogenocyclopropane into 4-fluoropyrimidine N-oxide. The difference in the reactivity of bis-cyclopropanes with different sets of halogen substituents leads to selective heterocyclization of bromofluorocyclopropanes without affecting the dichlorocyclopropane moiety.