Photoreaction of Phthalimides Possessing an ortho-Methylphenyl Group in Their N-Side Chain. Synthesis of Tetracyclic Nitrogen Heterocycles

Abstract

Upon irradiation phthaiimides (2 and 8) possessing an 9-methylphenyi group in therr N-side chain gave malniy the tetracycilc ring systems @ and 10). it was shown that the photocy~iization Occurs a t E-or S-posltion across the carbons of the benzene rlng (B ring). 2Photoreactions of phthaiimides (N possessing a certain functlonai group or a hetera atom, such as ~i e f i n .~ a n ~i l n o , ~ and methyithio5 in their N-side chain, have given r m to a variety of new heterocycles including large-sized ring systems.Among them, the phthaiimide (2) possessmg an pnethyiphenyi group in its N-side chain effectively undergoes &hydrogen abstraction t o give tetracycltc heterocycles, isoindoloindoione @) (Chart 1L6 Furthermore.~n order to extend this type of the reaction to a general synthesis of tetracyclic compounds havmg various ring size, photoreactions of phthaiimldes possessing an 2-methyiphenyi group in the N-side chain were investigated.in the presznt paper we wish to report