Palladium-Catalyzed Double Decarboxylative [3 + 2] Annulation of Naphthalic Anhydrides with Internal Alkynes.

A palladium-catalyzed [3 + 2] annulation of naphthalic anhydrides with internal alkynes has been developed. The present protocol offers an efficient and convenient route to access a series of 1,2-disubstituted acenaphthylenes with excellent functional group compatibility. The reaction is proposed to proceed through a double decarboxylation sequence. The reported synthetic protocols can be extended to napthalene- and perylenedicarboximide-containing substrates. The molecular structures, photophysical properties, and frontier molecular orbitals of the obtained adducts were investigated by X-ray crystallography, UV-vis and fluorescence spectroscopy, and DFT calculations.

Synthesis of Indolo- and Benzothieno[2,3-b]quinolines by a Cascade Cyclization of o-Alkynylisocyanobenzene Derivatives.

A new synthetic approach for the synthesis of indolo[2,3-b]quinolines and benzothieno[2,3-b]quinolines has been developed by employing the freshly prepared o-alkynylisocyanobenzenes derived from o-alkynylformamide derivatives as substrates. The synthetic transformations involved chloride-ion-triggered 6-endo cyclization of o-alkynylisocyanobenzenes to generate 2-chloroquinolines in situ, which further cyclized intramolecularly with nitrogen or sulfur atom via a cascade process to provide the corresponding indolo[2,3-b]quinolines and benzothieno[2,3-b]quinolines, respectively, in moderate to excellent yields.

Color-tunable emissive heptagon-embedded polycyclic aromatic dicarboximides.

Heptagon-embedded polycyclic aromatic dicarboximides were developed as new push-pull fluorescent dyes through palladium-catalysed [4+3] annulation followed by nucleophilic substitution. The introduction of a seven-membered ring in these push-pull systems can efficiently modulate the optical properties leading to an enhancement of the fluorescence quantum yields up to 0.93 with color tunable emission covering the visible-NIR spectrum.