Pentadienylnitrobenzyl and Pentadienylnitropiperonyl Photochemically Removable Protecting Groups

New photochemically removable protecting groups have been developed based on classical nitrobenzyl compounds modified by the inclusion of a pentadienyl group. It serves to trap through an internal Diels-Alder reaction the nitroso group produced as part of the photochemical deprotection process, preventing its further photochemistry or chemical reactions with nucleophiles.