Novel photolactonisation from xanthenoic esters

In the context of our work on photocleavable fragrance precursors, we have discovered a new photo-fragmentation of xanthenoic esters into xanthene- and formyl radicals. This homolytic cleavage has not been reported previously. Thus, unsaturated formyl radicals cyclise to lactones of various ring size. (C) 2001 Elsevier Science Ltd. All rights reserved.