INVESTIGATION OF THE REACTION OF 2-BROMO-1,4-DIMETHOXYNAPHTHALENE AND9-BROMOPHENANTHRENE WITH NITRILES UNDER ARYNE-FORMING CONDITIONS

The reaction of 2-bromo-1,4-dimethoxynaphthalene (1) and 8-bromophenan threne (3) with nitriles 2 under base-mediated, aryne forming conditio ns gives product distributions which depend upon the nature of the bro moarene, nitrile, base, and the reaction medium. Thus, treatment of 1 with arylacetonitriles 2a-d in the presence of LDA in THF or sodium am ide in liquid ammonia supplies alpha-aryl-1,4-dimethoxy-2-naphthylacet onitriles 4a-d, presumably by the aryne arylation mechanism. In contra st, the reaction of 9-bromophenanthrene (3) and arylacetonitriles 2b-e with LDA in THF yields 10-arylmethyl-9-phenanthrenecarbonitriles 6b-e , most likely by the tandem addition-rearrangement pathway. When 3 rea cts with 2a-c in the presence of sodium amide and liquid ammonia, alph a-aryl-9-phenanthrylacetonitriles 5a-c, rather than the rearranged nit riles 6a-c, are obtained. Both 1 and 3 react with alkylnitriles 2f-i a nd LDA-THF, sodium amide-liquid ammonia, or Caubere's sodamide base to afford aryne arylated nitriles (4f-i and 5f-i, respectively). An expl anation in terms of the influence of reactants and solvent on the comp etition between the aryne arylation and tandem addition-rearrangement pathways is presented.