Controlled release of volatile compounds using the Norrish type II reaction

The Norrish type II photofragmentation of 1-phenylalkan-1-ones (phenyl alkyl ketones) or 2-oxoacetates (α-ketoesters) is useful to control the release of volatile compounds from surfaces exposed to daylight. The reaction proceeds in the UV-A region of the solar spectrum and tolerates the presence of oxygen and water. Suitably designed photocages allow the generation of alkenes, aldehydes, ketones, esters or lactones. Mechanistic aspects are discussed in view of using the corresponding light-responsive profragrances or properfumes as delivery systems in practical applications.