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In this paper, we document the construction of functionalized and fused eight-membered carbocycles by the triflic anhydride-mediated cyclization of 7-enamides. Taking advantage of the high electrophilicity of the nitrilium ion intermediates, generated in situ from secondary N-(2,6-dimethyl)­anilides, the nonactivated, trisubstituted alkene–nitrilium cyclization reactions proceeded smoothly to afford nonconjugated β,γ-enimines (for fused 6/6/8 ring systems), conjugated α,β-enimines (for 6/5/8), or fused 5/8 ring systems in good yields. When the cyclization reactions were followed by one-pot acidic hydrolysis, the reaction led directly to the corresponding α,β-enones. For some substrates, the reaction afford an efficient access to pendent cyclic β,γ-enimines/enones.

A facile and efficient synthesis of bicyclic 1,3-oxazin-4-ones, 2,3,6,7-tetrahydrocyclopenta[e]-1,3-oxazin-4-ones and 2,3,5,6,7,8-hexahydro-4H-benzo[e]-1,3-oxazin-4-ones has been achieved via Ir-catalyzed one-pot reaction of secondary amides with adipoyl chloride and pimeloyl chloride, respectively. This method...