ON THE SYNTHESES AND PHOTOCHEMICAL PROPERTIES OF NOVEL PYRROLIZINONE DERIVATIVES AS PHOTOSENSITIZERS

The syntheses of the pyrrolizinone derivatives 8H-6-methyl-7-phenylthi eno2,3-b!-pyrrolizin-8-one (1), 9-tetrahydro(1)benzothieno2,3-b!pyrr olizin-10-one (2), 8H-6-phenylthieno2.3-b!pyrrolizin-8-one (3), 8H-me thylthieno2,3-b!pyrrolizin-8-one (4), are described. In contrast to b enzophenone, compounds 1 - 4 absorb in the visible light region (epsil on436 nm - = 400, 420, 450, and 320 1 mol-1 cm-1 for compounds 1 - 4, respectively). 9-Fluorenone as well as compounds 1 - 4 were able to re duce methylviologen in the presence of 2-propanol under irradiation wi th UV light (A > 280 nm). Compounds 1 - 4 showed an interesting fluore scence behavior depending on solvent and on Ph - value, which will be discussed in detail.