Pentalenes with novel topologies: exploiting the cascade carbopalladation reaction between alkynes and gem-dibromoolefins

A series of π-extended pentalenes with fused naphthyl-ring systems in different geometries were synthesised via a cascade carbopalladation reaction between alkynes and gem-dibromoolefins. This novel methodology was applied both in an intermolecular and an intramolecular fashion to access pentalenes with new topologies. The relationship between the fusion pattern and the opto-electronic properties within the synthesised series was investigated by UV/vis spectroscopy and electrochemical techniques. Novel pentalene reactivity, leading to yet unprecedented derivatives, was also uncovered.