Light-sensitive amides. Photocleavage of N-acyl-1,2,3,4-tetrahydro-8-nitroquinolines to give free carboxylic acids

Abstract

The structural assignments of the 5- and 8-nitrotetrahydroquinolines have been reversed on the basis of their n.m.r. and mass spectra. U.v. irradiation cleaved the amide bonds of N-acyl-8-nitrotetrahydroquinolines to furnish free carboxylic acids in high yields, thus indicating the potential of 8-nitrotetrahydroquinolyl as a photosensitive protecting group for carboxylic acids. It has been shown that the release of the carboxylic acids involves a photocleavage and not a solvolysis. It has been experimentally demonstrated for the first time that oxygen transfer takes place from an excited nitro-group. This process precedes hydrogen abstraction and both processes are intramolecular.