Formation of cyclooctatriene and bicyclooctadiene through regioselective intermolecular (2 + 2) photocycloaddition of benzoic acids to allyl alcohol in water

The regioselective intermolecular (2 + 2) photocycloaddition of the sodium salt of benzoic acids 1 to allyl alcohol 2 proceeded in water to afford cyclooctatrienes 3 and bicyclooctadienes 4. The efficiency and product distribution of this photoreaction were strongly influenced by the substituent of benzoic acid and solvent polarity. The photocycloaddition of benzoic acids in water is an environmentally friendly method for the preparation of cyclooctatriene and bicyclooctadiene.