Stable Monoareno-pentalenes with Two Olefinic Protons.

A novel class of stable monoareno-pentalenes is introduced that have an olefinic proton on each five-membered ring of the pentalene subunit. Their synthesis was accomplished via a regioselective carbopalladation cascade reaction between ortho -arylacetyleno gem -dibromoolefins and TIPS-acetylene. These molecules could be experimental probes of magnetic (anti)aromaticity effects.