[摘要]：A tandem three-component coupling photoreaction proceeds upon photoirradn. of MeCN/H2O solns. contg. propanedinitrile (1, malononitrile), 2,5-dimethylhexa-2,4-diene (2), and polycyano arenes in the presence of phenanthrene and carbonate, leading to selective a-monoalkylation of 1. The reaction proceeds via photo-NOCAS (Nucleophile-Olefin Combination, Arom. Substitution) type mechanism: nucleophilic attack of the anion of 1 to photogenerated 2? is followed by ipso-substitution on the radical anion of the polycyano arene. It advances under mild, safe, and environmentally friendly conditions such as proceeding at ambient temp. without metals and halogens, and in the presence of weak base. The reaction also represents a novel and metal-free cross-coupling reaction that leads to ipso-substitution on polycyano arene via aryl-cyano bond cleavage. In addn., the reaction is a rare example of introducing carbon nucleophile in the photoinduced electron transfer reaction, except that of cyanide ion.
