A photo-sensitive protecting group for amines based on coumarin chemistry

Abstract

There is a continuing need for the development of new protecting groups for amines which can be cleaved under conditions that are mild and fundamentally different from what are already available. In this paper, we report our studies in using o-hydroxy-trans-cinnamic acid as a photo- sensitive protecting group for amines. The design takes advantage of the trans-cis photo-isomerization and the ensuing facile lactonization of o- hydroxy-cis-cinnamic acid and derivatives. We have found that both the protection and deprotection can be carried out in high yields for a variety of amines with different structural features. The deprotection reaction uses low intensity UV light (365 nm), which is fundamentally different from the conditions used for the deprotection of other commonly used amino-protecting groups. Therefore, the method complements other available methods in allowing for selective manipulation of different functional groups in a complex organic molecule.