Photochemistry of allenyl salicylaidehydes

The intramolecular photocycloaddition of aryl aldehydes containing allene side chains is a versatile reaction as it provides a rapid and efficient access to original complex structures such as 1,3,4-tetrahydro-1,4-epoxy-5-alkylidene-2-benzoxepines 2 and substituted 2-oxa-tricyclo[5.2.2.0](1,5)undeca4,8,10-triene-9-carbaldehydes 3. Novel polycyclic structures are characterized, and optimized strategies for the synthesis of the substrates 1 are described.