Nickel-Catalyzed, Cascade Cycloadditions of 1-Ethynyl-8-halonaphthalenes with Nitriles: Synthesis, Structure, and Physical Properties of New Pyrroloarenes
The reaction of 1‐ethynyl‐8‐halonaphthalenes 1 with nitriles in the presence of the catalytic system [NiBr2(dppe)]/Zn (dppe=1,2‐bis(diphenylphosphino)ethane) is found to produce unusual pyrroloarenes 2. The carbon–nitrogentriplebond in nitrile is activated twice, and five new bonds are formed in a one‐pot transformation, which causes a pyrrole and two six‐membered rings to be generated simultaneously
Zethrenes were synthesized by Pd‐catalyzed cyclodimerization of 1‐ethynyl‐8‐iodonaphthalenes. The structure of these cycloadducts was confirmed by X‐ray crystal analysis. The bond lengths and bond alternation in the crystal structures reveal that the central two six‐membered rings of the title compounds lack aromaticity.