Estudio teórico de la regioselectividad de la boldina en reacciones de sustitución aromática

The nitrosation of boldine with nitrous acid in acetic acid and its halogenation with molecular bromine or N-halosuccinimides (halo = Cl, Br, I) in acetic or trifluoroacetic acid exhibit different regioselectivities. Thus, we found that experimentally boldine proceed with Br₂ and N-halosuccinimide affording mono-substituted products in C-3 being attributable to the formation of an electron transfer mechanism (ET) while its nitrosation reaction should proceed by electron transfer within an electron donor-acceptor (EDA) complex that precedes the aromatic substitution step. The regiochemistry of the aromatic substitution is explained by Wheland complex and using reactivity descriptors such as electrophilic and free radical superdelocalizabilites.