The photochemical behaviour of 2-EWG-substituted heterocycles in the presence of alkenes and alkynes

Article abstract of DOI:10.1016/S0040-4020(98)01215-0

The photochemical reaction of some halogenoheterocycles substituted with electron withdrawing groups with acrylonitrile gave the addition product in high yields. The irradiation of 2-acetyl-5-phenylthiophene at 355 nm with a Nd:YAG laser in the presence of phenylacetylene gave 1-phenylnaphthalene, probably formed the triplet state of phenylacetylene. 2-Acetyl-5- phenylthiophene is a sensitizer for this reaction. The irradiation of 2- nitro-5-phenylthiophene and 2-nitro-2',5-bithienyl in the presence of arylalkynes gave products from an oxidation reaction of the alkynes. The sensitization of phenylacetylene triplet can be explained assuming the population of a higher triplet state.