Fluorocarbanion Chemistry. Octafluorofluorene and Companions

Article abstract of DOI:10.1021/jo01295a025

Octafluoro-9-fluorenone (2) is obtained by reaction of 2-bromoctafluorobiphenyl-2'-carboxylic acid (4) with n-butyllithium.The reaction illustrates an unusual intramolecular nucleophilic arylation involving attack at a carboxylate salt.Catalytic reduction gives octafluoro-9-fluorenol, rather than octafluorofluorene (1). 1 is synthesized by a six-step procedure from 2-bromnonafluorobiphenyl (7).The key step involves an intramolecular nucleophilic alkylation to form ethyl octafluorofluorene-9-carboxylate (12), which rapidly undergoes decarboxylative hydrolysisin both alkaline and acidic media to form 1.Relative to the 9-fluorenyl system and open-chain polyfluorinated analogues, 1 and 12 exhibit anomalous reaction chemistry, owing to the exceptional stabilities of their anions.