Naphthalene derivatives peri-substituted by Group 13 elements

This review focuses on the chemistry of naphthalene derivatives substituted by Group 13 moieties at the peri-positions. Depending on the nature of the Group 13 elements, different synthetic approaches have been considered. 1,8-Diborylated naphthalene complexes are conveniently prepared by metathesis of boron halides or alkoxides with 1,8-dilithionaphthalene. Such complexes can also be obtained by ring opening reaction of 1,8-boron bridged naphthalene species. Owing to the proximity of the boryl moieties, these derivatives are often sterically congested. Gallium and indium derivatives have also been prepared. In this case, however, alternative synthetic approaches have been used. These derivatives can be obtained by reaction of GaCl3 or InCl3 with 1,8-bis(trimethylstannyl)naphthalene. The transmetalation reaction of indium(I) halides with 1,8-bis(halomercurio)naphthalene has also proved useful for the synthesis of naphthalenediylindium complexes. While the development of various applications is still being explored, the 1,8-diborylated naphthalene complexes serve as bidendate Lewis acidic hosts for neutral and anionic guests. Recently, such complexes have also served to provide a scaffold for the formation of radicals that feature intramolecular one-electron sigma-bonds. (C) 2002 Elsevier Science B.V. All rights reserved.