Photoacid-catalyzed acetalization of carbonyls with alcohols.

In this report, we demonstrate that visible light photoactivation of 6-bromo-2-naphthol facilitates the photoacid-catalyzed acetalization of carbonyls with alcohols. We also demonstrate that 2-naphthol when coupled to a photosensitizer provides acetals from electron-deficient aldehydes. In addition, the S excited state p for 6-bromo-2-naphthol in water was determined and shown to have increased excited-state acidity relative to 2-naphthol.