Triphenylmethyl hexafluorophosphate

When cycloheptatrienyllithium is added to tetrabutylammonium bromopenta-carbonyltungstate in THF at —7S°C a cycloheptatrienyltungstate is obtained which can be converted with triphenylmethyl hexafluorophosphate via hydride abstraction into a pentacarbonylcarbene complex ... 

KETONES Lithium diisopropylamide. Nickel carbonyl. Sodium tetracarbonyl-ferrate(-II). Thallium(III) nitrate. 2,4,4,6-Tetramethyl-5,6-dihydro-l,3-(4 I)-oxazine. Triphenylmethyl hexafluorophosphate. y-KETONITRILES Sodium cyanide. (3-LACTONES Silver nitrate. y-LACTONES a-Chloro-N-cyclohexylpro-panaldoxime. 

Hydride abstraction from dienyl tricarbonyl iron complexes furnishes cationic dienyl tricarbonyl iron complexes. For example, reaction of the diene - iron tricarbonyl complex (115) with triphenylmethyl hexafluorophosphate followed by trimethylsilyl cyanide furnished with excellent regio- and stereoselectivity a new diene-iron tricarbonyl complex (116) (Scheme 170). Excellent regio- and stereoselectivity is seen upon reaction of the cationic complex (116) with trimethylsilyl cyanide (TMS-CN) (Scheme 170). Reduction of the nitrile affords a spirocyclic lactam complex. Intramolecular cyclization of in situ formed enols furnishes spirocyclic compounds again with excellent stereocontrol (Scheme 171). An interesting example of hydride transfer from a cyclohexadiene ring to a pendant aldehyde followed by nucleophilic addition is seen in Scheme 172. 

The cation (XXXIV) was obtained by deprotonation of a benzocyclo-butenocycloheptatriene, using triphenylmethyl hexafluorophosphate [196], N.m.r. spectra indicate that it is best regarded as possessing two essentially independent 6 ir-electron systems. A benzo--derivative of (XXXIV) has also been prepared in solution [197]. 

In this case, a preliminary alkylation of the thioether group by triphenylmethyl hexafluorophosphate, Meerwein s salt, or dimethoxycarbenium tetrafluoroborate induces the process. The dimethylthiosulfonium complexes are versatile and easy-to-handle precursors to generate the corresponding (methylene)iron complex in situ, which can be used for the cyclopropanation of alkenes (Scheme 4-58). 

Several catalysts and initiator systems have been tested for the polymerization of GlcAnBzl3, including the following Lewis acids boron trifluoride and its etherate, phosphorus pentafluoride, titanium tetrachloride, and antimony pentachloride and pentafluoride. Several cationic initiators have also been used, including (triphenylmethyl) antimony hexachloride, 2,3,4,6-tetra-O-acetyl-D-glucopyranosyl hexa-fluorophosphate, acetyl hexafluorophosphate, pentamethylbenzyl hexa-fluorophosphate (most of which were generated in situ), and triethyl-... 

Triphenylmethyl, tropylium, xanthylium, acylium and diazonium salts have also been used successfully in the study of the polymerization of THF [50]. In fact the true equilibrium conversions were first demonstrated using p-chlorophenyl diazonium hexafluorophosphate [41, 115], and at the same time the polymerizations were shown to be living . The lower equilibrium yields [50] observed when other counter-ions are employed, e.g. SbClg, appear to arise because of a termination mechanism associated with the anions. Kinetic studies [50] of the polymerization of bulk THF with Phg C SbCl have established the apparent rate law... 

Polymerizations of tetrahydrofuran with the aid of chlorobenzene diazonium hexafluorophosphate [343], triphenylmethyl hexachloroantimonate [344], or phosphorus pentafluoride [445]. 

---