Complexes reactions with hexafluoroacetone

Pentaazadienes, structure, 32 171-172 Pentaborane(9) reaction of with alkynes, 26 74 Pentacarbonyltungstenhydrogen sulfide anion, reaction with hexafluoroacetone, 30 297 Penta-coordinate complexes, 4 175-178 Pentacyanides... 

Phosphide-bridged complexes, osmium, 37 311 Phosphinates and phosphinites, reaction with hexafluoroacetone, 30 235 Phosphines, 44 318... 

A behavior similar to that of pyridine and pyrazine N-oxides is exhibited by complexes of pyridines with hexafluoroacetone. Such complexes are expected to enhance the acidity of the pyridine hydrogens by oxygen-lithium chelating effects and therefore direct 2-deprotonation. In fact, treatment of f-butylpyridine (495) with LiTMP/THF-Et20/- 107°C generated, via the known complex 507, the stable 2-lithio species 508 which, upon reaction with electrophiles, furnished 2-substituted pyridines 509 (Scheme 154) (83JOC4156). 

At -107°C, reaction of hexafluoroacetone-complexed pyridine with LiTMP followed by MeOD as the electrophile gave 90% C-2 deuteriation, whereas at -78°C, C-2 (48%) and C-4 (28%) deuterium incorporation was observed. 

Hexafluoroisopropylideneamine reacts with Pt(trans-stilbene)(PPh3)2 to give the r 2-bonded complex (86 equation 261).790 As with hexafluoroacetone, addition of a second molecule of (CF3)20=NH gives platinacycles. The formation of (86) contrasts with the reaction of Pt(PPh3)2 with iminium salts [Me2N=CH2]Cl where the first product is the platinacycle (87 equation 262).791... 

Reactions with fluoride ion With the exception of CF3OH (see the next section), fluorinated alcohols of the type RpCF20H are not known [124] but complexes of K, Rb, Cs, Ag or (C2H5)4N+ fluorides with hexafluoroacetone have been isolated [125, 126], following from the earlier isolation of some similar complexes with carbonyl fluoride [127]. These complexes have been reasonably formulated as fluorinated alkox-ides (Figure 8.27), but the use of these salts in synthesis is often difficult because the complexes may also act as fluoride-ion donors [128]. 

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