Oskar Jeger

Photochemistry of 5.6-epoxy-1,3-dienes : Influence of a 7-hydroxy substituent

Abstract Triplet sensitization of the 7-hydroxy-5,6-epoxy-1,3-diene 10 causes cleavage of the C(5),0 epoxide bond followed by the formation of the three isomers 11 – 13 or induces scission of the C(6), C(7) bond followed by the formation of the aldehyde 14 and the bicyclo[3.2.0]heptanols 15 and 16 . However, irradiation of the corresponding acetate 18 gives only C(5),0 epoxide bond scission ( 18 → f ) followed by the cyclization process f → 19 , the 1,2-Me shifts f → 20 , 21 and the γ-H abstraction f → g leading to the cyclopropane formation g → 22 .