Trityl hexafluorophosphate

Triphenylmethylium (trityl) hexafluorophosphate may be obtained commercially (Aldrich) or prepared by the following adaptation of Dauben s original synthesis.9 A 1-L Erlenmeyer flask containing 200 mL of acetic anhydride is immersed in an ice-water bath, and with gentle swirling, (21 mL of 65%) aqueous H[PF6] is added dropwise. 

Synthesis of aldehydes and ketones. Trityl ethers disproportionate to triphenyl-methane and aldehydes or ketones in the presence of small amounts of trityl salts trityl hexafluorophosphate, trityl hexafluoroantimonatc, (CsHjIjC AbFft , or trityl hexafluoroarsenate, (C H 5)jC AsFj,". 

Trityl hexafluoroantimonate, (CeHsljC SbF ", and trityl hexafluorophosphate, (C5ll5)3C Pf4", can be prepared in the same way using anhydrous fluoroantimonic acid and the ether complex of hexalluorophosphoric acid, respectively. 

Hydridophosphine complexes. Proton abstraction from [RuH2(PPh3)4] using trityl hexafluorophosphate in dichloromethane has yielded the new five-co-ordinate cation [RuH(PPh3)4]PF5. ° Since this cation reacts with smaller phosphines or nitriles to give six-co-ordinate cations [RuHLj] and [RuH-(RCN)2(PPh3)3], respectively, the failure to obtain [RuH(PPh3)5]" is... 

The reaction of trityl hexafluorophosphate and THF has been shown to proceed without evidence of a termination reaction, and a living cationic system can be obtained. The reaction takes place below room temperature. 

Benzyl trityl ether added to a stirred soln. of trityl hexafluorophosphate in anhydrous acetonitrile, and the product isolated after 4 hrs. at room temp. -> benzaldehyde. Y ca. 100%. F. e. triphenylcarbonium salts s. M. P. Doyle, D. J. DeBruyn, and D. J. Scholten, J. Org. Chem. 38, 625 (1973). 

Protonic initiation is also the end result of a large number of other initiating systems. Strong acids are generated in situ by a variety of different chemistries (6). These include initiation by carbenium ions, eg, trityl or diazonium salts (151) by an electric current in the presence of a quartenary ammonium salt (152) by halonium, triaryl sulfonium, and triaryl selenonium salts with uv irradiation (153—155) by mercuric perchlorate, nitrosyl hexafluorophosphate, or nitryl hexafluorophosphate (156) and by interaction of free radicals with certain metal salts (157). Reports of "new" initiating systems are often the result of such secondary reactions. Other reports suggest standard polymerization processes with perhaps novel anions. These latter include (Tf)4Al (158) heteropoly acids, eg, tungstophosphate anion (159,160) transition-metal-based systems, eg, Pt (161) or rare earths (162) and numerous systems based on tri flic acid (158,163—166). Coordination polymerization of THF may be in a different class (167). 

Peptide coupling reagent bromotris(pyrrolidino)phosphonium hexafluorophosphate (PyBrOP) was used in synthesis of 10-membered succinyl bis(amide) 27 in 57% yield (Equation 3) <2002TL2593>. Similarly, 1,6-diazacyclo-decane substituted on only one nitrogen atom was prepared by reaction of A -trityl-protected linear triamine with succinyl anhydride. The amides were further reduced to amines using LAH <2002TL2593>. 

Figure 7.9 Synthesis of PC2. DMF = dimethylformamide Fmoc = 9-fluorenylmethoxycarbonyl Tit = trityl DEEA = diisopropylethylamine NMP = /V-methylpyrolidine. HBTU = 0-(benzotriazol-l-yl)-/V./V./V. /V,-tetramethyluronium hexafluorophosphate.

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