Syntheses and characterization of bis(trifluoromethyl)phosphino naphthalenes and acenaphthenes

Abstract

Syntheses of heteroleptic 1,8-bis(phosphino)naphthalenes and 5,6-bis(phosphino)acenaphthenes were attempted using several synthetic strategies. Reaction of aryllithium with triphenylphosphite gave ArP(OPh)₂ (Ar = substituted naphthalene or acenaphthene), which was transformed into ArP(CF₃)₂, using a nucleophilic trifluoromethylation reaction with Me₃SiCF₃/CsF. The importance of the correct choice of solvent for the trifluoromethylation reactions is discussed. The incompatibility of ArP(CF₃)₂ with organolithium hampered the attachment of the second phosphine functionality to the organic backbone. Tetraphenoxyethylene was obtained in a small amount as a side product in the trifluoromethylation reaction. Selected new compounds were characterized by single-crystal X-ray diffraction.