Abstract: The photochemical reaction of 3-acetylcoumarin and its 7-acetyloxy,7-benzoyloxy,6-bromo and 5,6-benzo derivatives with indole in solid state gave only condensation products,while 3.acetyl-6-nitrocoumarin with indole gave ring-cleavage decarbonyl addition product in the solid state,3-Acetylcoumarin and its derivatives with indole can not undergo photochmical reaction in solution.The solid-state photochemical reaction shows a high selectivity.The effect of the nature of substituent and the position of substitution were also investigated,the withdrawing substituent facilitate the photoreaction and there is a higher reactivity of acetyl at position₃ than at position 6 and 8.The structures of six new products were identified by IR, MS,¹H NMRand elemental analvsis.

Key words: Coumarin, Indole, Solid state photoreaction