Base-mediated cyclization reaction of 2-alkynylphenylphosphine oxides:: Synthesis and photophysical properties of benzo[b]phosphole oxides

The base-mediated intramolecular cyclization reaction of 2-alkynylphenylphosphine oxides affords benzo[b]phosphole oxides, which show intense blue-green fluorescence. Benzo[b]phospholes are also prepared by the reduction of benzo[b]phosphole oxides.