Synthesis and reaction mechanism of a photoremovable protecting group based on 1,4-naphthoquinone

5-(ethylen-2-yl)-1,4-naphthoquinone () is a photoremovable protecting group that absorbs up to 405 nm and provides fast and efficient release of bromide or diethyl phosphate. A convenient synthetic protocol to three derivatives of is described and their photochemistry in aqueous and acetonitrile solutions is investigated. The photoenol intermediates that expel the protected substrates were detected by laser flash photolysis and step-scan FTIR spectroscopy. The nucleofugacity of the leaving group and pH are the major factors that determine the reaction pathway.