?-Fluoroalkylamines, a new source of unhydrated fluoride ion. Communication 6. hexamethylguanidinium fluoride

Fluorination Triggers Fluoroalkylation: Nucleophilic Perfluoro‐tert‐butylation with 1,1‐Dibromo‐2,2‐bis(trifluoromethyl)ethylene (DBBF) and CsF

“…We combined DBBF (0.6 mmol) and CsF (2.0 mmol) in DMF, and stirred for 1 h at room temperature. A broad singlet at around À43.2 ppm was observed (using CCl 3 F as an internal standard at 0.0 ppm), which matched the previously reported data [17] and was assigned as the "CsC(CF 3 ) 3 " species. It is noteworthy that the "CsC(CF 3 ) 3 " species was relatively stable and could be stored at À20 8C for at least 50 hours without loss of reactivity for perfluoro-tert-butylation of the model substrate 1 a (Figure 1 b).…”

Hexaalkylguanidinium and 2-(Dialkylamino)-1,3-dimethylimidazolinium Trimethyldifluorosiliconates and Perfluoroalkoxides. Accidental Isolation and Molecular Structure of [C(NMe2)3]+F-·6CH2Cl2

“…The chemistry of the previously synthesized hexameth-ylguanidinium fluoride (HMGF) has not been developed, apparently because of its difficult access from HMG + pivaloate and Et 2 NSF 3 and the extreme basicity of HMGF. 23 In contrast to (Me 2 N) 3 C + F -, which shows a 50% HF 2impurity even in DMF solution, 23 It was quite surprising that (Me 2 N) 3 C + Fdoes not fluorinate methylene chloride at -30 °C. In this case HMGF is similar to Me 4 NF which fluorinates CH 2 Cl 2 at ambient temperature, 34 but its methylene chloride solution obtained at -30 °C is stable at this temperature for many hours.…”

“…The chemistry of the previously synthesized hexamethylguanidinium fluoride (HMGF) has not been developed, apparently because of its difficult access from HMG + pivaloate and Et 2 NSF 3 and the extreme basicity of HMGF due to F - complexation with Me 3 SiF, the basicity of (Me 2 N) 3 C + Me 3 SiF 2 - is reduced compared with HMGF. In our case no significant HF 2 - concentration in (Me 2 N) 3 C + Me 3 SiF 2 - solutions was detected; e.g.…”

“…The perfluorinated carbanionic species HMG + [C(CF 3 ) 3 ] -, prepared from HMG + HF 2or HMG + Fand perfluoroisobutene, was found to be a stable solid. 22,23 The lipophilic and robust HMG + could be the cation of choice to get stable HMG + perfluoroalkoxides since the positive charge is distributed over three nitrogen atoms. Searching for a general route to pure hexaalkylguanidinium fluorides containing no HF 2as precursors for hexaalkylguanidinium perfluoroalkoxides avoiding SF 4 and its derivatives, we decided to study the reactions of bis(dialkylamino)methane derivatives with (dialkylamino)trimethylsilanes.…”