REGIOCHEMISTRY OF THE COUPLING OF ARYL RADICALS WITH NUCLEOPHILES DERIVED FROM THE NAPHTHYL SYSTEM - EXPERIMENTAL AND THEORETICAL-STUDIES

We here report the photostimulated reaction of unactivated aromatic halides with ambident nucleophiles derived from the naphthyl system such as 1- and 2-naphthylamide, 2-naphthoxide, 2-naphthalenethiolate, and 2-naphthaleneselenate ions, by the S(RN)1 mechanism of nucleophilic substitution. According to our experimental results, C-arylation in position 1 of the naphthyl moiety is the only reaction observed with 2-naphthoxide ions and it is favored over N-arylation with 1- and 2-naphthylamide ions. Heteroatom arylation is preferred over C-arylation with 2-naphthalenethiolate ions while it is the only observed reaction with 2-naphthaleneselenate ions. A theoretical study was carried out to explain the regiochemistry of the system. In competition experiments, 2-naphthalenethiolate ions proved to be 1.8 +/- 0.2 times more reactive than 2-naphthoxide ions for C-substitution toward p-anisyl radicals in liquid ammonia.