Neighboring group effect of pyridazine and pyrazine rings for π-facial selectivity in the reactions of fused isopropylidenenorbornene systems with electrophilic reagents
the electrophilic reactions with 4-phenyl-1,2,4-triazole-3,5(4H)-dione (PTAD), m-chloroperbenzoic acid (MCPBA) and N-bromosuccinimide (NBS) has been investigated. The ene reactions with PTAD exhibited exclusive syn selectivity to the heteroaromatic rings except for an isopropylidenenorbornene fused with a pyridazine N-oxide ring. The epoxidations with MCPBA and the ene reactions with NBS afforded mixtures