N-HALOGENO COMPOUNDS. PART 12. SITE-SPECIFIC FLUORINATION OF CARBANIONS WITH PERFLUORO-N-FLUOROPIPERIDINE

Article abstract of DOI:10.1016/S0022-1139(00)80353-X

Perfluoro-N-fluoropiperidine (1) acts as a site-selective electrophilic fluorinating agent towards carbanionic substrates Me2CFNO2; PhMgBr -> PhF; PhCNa(CO2Et)2 -> PhCF(CO2Et)2; EtCNa(CO2Et)2 -> EtCF(CO2Et)2; <*> -> <*>>, but in doing so is converted to perfluoro-1-azacyclohexene (2).Unfortunately, this imidoyl fluoride (2) is highly electrophilic and competes with the N-F compound (1) for carbanionic species, as examplified by the formation of the 2-substituted octafluoro-1-azacyclohexenes <*>, where R = Ph, CEt(CO2Et)2, and <*> in the respective cases of the last three sodio derivatives listed above.