Linear Extension of Carbaporphyrin Chromophores: Synthesis, Protonation, and Metalation of Anthro[2,3-]carbaporphyrins: Evidence for 30π-Electron Aromatic Circuits in a Palladium(II) Complex.

Acid-catalyzed condensation of a naphtho[2,3-]indane dialdehyde with a tripyrrane, followed by an oxidation step, afforded an anthro[2,3-]-21-carbaporphyrin. The presence of a fused anthracene unit induced minor bathochromic shifts and did not significantly affect the aromatic characteristics of the carbaporphyrin core. Protonation led to the formation of a monocation with similar diatropic properties, but the dication generated in the presence of a large excess of trifluoroacetic acid had a weakened Soret band absorption and a broad absorption at 754 nm.

Oxidopyrylium-Alkene [5 + 2] Cycloaddition Conjugate Addition Cascade (C) Sequences: Scope, Limitation, and Computational Investigations.

Oxidopyrylium-alkene [5 + 2] cycloaddition conjugate addition cascade (C) sequences are described. Intramolecular cycloadditions involving terminal alkenes, enals, and enones were investigated. Substrates with tethers of varying lengths delivered five- and six-membered carbocycles and heterocycles thus demonstrating the scope and limitation of the cycloaddition-conjugate addition cascade.