Halogen Electrophile Induced Cyclization Route to Isoquinoline N-Oxides

Significance

The present article describes an electrophilic cyclization between ortho-alkynylbenzaldehyde oximes and various halogen electrophiles to afford 4-halo-isoquinoline N-oxides. The substrate scope was adequately studied and the yields range generally from good to excellent, an exception being the case of R^¹ = 4,5-(OCH₂O), R^² = Ph and electrophile = Br₂ (25% yield). The utility of the products was shown in further Pd-catalyzed Suzuki-Miyaura cross-coupling reactions to give 4-aryl products.