Pentafluorophenylmagnesium bromide

FLUORINECOMPOUNDS,ORGANIC - FLUORINATED AROMATIC COMPOUNDS] (Volll) Pentafluorophenylmagnesium bromide [879-05-0]... 

Pentafluorophenylmagnesium bromide or lithium can be converted to other pentafluorophenyl organometabics by reaction with the corresponding metal chloride (237). Bis(pentafluorophenyl)phenylphosphine [5074-71-5] (Ultramark 443), (CgF )2CgH P, is offered commercially as a marker for mass spectral standardi2ation (238). 

A method for generating a perfluoroarylmagnesium compound is the cleavage of a pentafluorophenyl-metal bond by a nucleophile such as ethyltnagnesium bromide As an example, tetrakis(pentafluorophenyl)tin on reaction with ethyl-magnesium bromide gives a series of products, one of which may result from pentafluorophenylmagnesium bromide [27] (equation 7)... 

Pentafluorophenylcopper exists as a tetramer. It forms complexes with a variety of reagents and solvents as well as ate complexes a representative list is given in Table I. For many syntheses the crude reaction mixtures of cuprous halide with either pentafluorophenylmagnesium bromide, or pentafluorophenyllithi-um, or the pentafluorophenylcopper-dioxane complex react as well as the solvent-free tetramer. 

Brewer, Heaney, and Marples 103> were able to isolate the mono adduct 142 from the reaction of tetrafluorodehydrobenzene (141) with [2.2]para-cyclophane. The 2 1 adducts 143 and 144 were obtained when an excess of pentafluorophenylmagnesium bromide was employed. 

In contrast to the extensive investigation of fluorovinylzinc reagents and their synthetic utility, only limited literature exists on fluorinated arylzinc reagents. Bis(pentafluorophenyl) zinc can be prepared by the reaction of zinc chloride with either pentafluorophenyllithium or pentafluorophenylmagnesium bromide (equation 70)64,65. An alternative route is via decarboxylation of zinc bis(pentafluorobenzoate) (equation 71)65. 

The nature of organocopper reagents appears to be dependent on the method of preparation and the stoichiometry. Specific examples are methylcopper (76, 310), phenylcopper 73), and pentafluorophenyl-copper 34, 37, 147). The best method of preparing pentafluorophenyl-copper of composition CeFsCu appears to be via the addition of copper(I) bromide to pentafluorophenylmagnesium bromide 34, 37), since the lithium reagent and copper iodide gives an ate complex 147). An ate complex was also obtained from pentafluorophenyllithium and silver chloride in equimolar proportions 265). As shown in Table III, many of the isolated copper compounds gave somewhat incorrect or irreproducible analyses, and others contain metal halide and solvent molecules. 

A similar process, but involving further attack on the biphenyl and polyphenyls initially produced, may account for the high-molecular-weight materials formed in the decomposition of pentafluorophenylmagnesium bromide at elevated temperatures in THF solution [230, 231] (Figure 9.90). 

An attempt to prepare tetrakis(pentafluorophenyl)lead analogously from lead dichloride, pentafluorophenyllithium, and pentafluoroiodobenzene failed, although the action of pentafluorophenylmagnesium bromide on lead dichloride in the presence of benzyl chloride gave the mixed organolead compound ... 

Dialkyl- and diaryl-chloroarsines are formed in good yield from dichloro-(A,iV-dialkylamino)arsines and organo-magnesium or -lithium compounds.493 Dichloro(pentafluorophenyl)arsine and chlorobis(pentafluorophenyl)arsine are obtained analogously from pentafluorophenylmagnesium bromide and arsenic trichloride or dichloro-(A,iV-dimethylamino)arsine.494... 

Cyanohydrins. The organotin compound catalyzes the Mukaiyama aldol reaction, the derivatization of carbonyl compounds with MejSiCN, and other Lewis acid-catalyzed processes at -78°. It is prepared from diallyltin dibromide by reaction with pentafluorophenylmagnesium bromide followed by bromolysis. 

Pentafluorophenylethanol, obtained by the established route from pentafluorophenylmagnesium bromide and acetaldehyde or from penta-fluorophenylmagnesium chloride and ethylene oxide in hydrocarbon solvents, has been converted by conventional methods into 2-pentafluorophenyl-n-propylamine [ROH RBr RCN RCH, NH, (R = C,Fs CHMe)). Cyclization of the amine (KF-DMF) gives the dihydroindoie (203), converted by dehydrogenation (Pd/Q into 4,5,6,7-tetrafluoro-3-methylindole... 

Cobalt, Rhodium, and Iridium.— Reaction of pentafluorophenylmagnesium bromide with CoBra in THF apparently yields bis(pentafluorophenyl)cobalt, which is stable in THF solution but cannot be isolated as such. However, addition of tri-n-butylphosphine yields the stable complex [(Bu"sP)2Co(C6Fb)2], also available by reaction of CeFgMgBr with (Bu"aP)2CoBr2. Bis(pentafluorophenyl)cobalt yields pentafluorobenzene with water, with oxygen yields perfluorobiphenyl (69%) and theperfluoro-... 

Preparation by demethylation of 2,3,4,5,6-penta-fluoro-2 -methoxybenzophenone (SM) in methylene chloride in the presence of aluminium chloride at 20 for 3-6 h (68%) [570], SM was obtained in two steps first, preparation of 2 -methoxy-2,3,4,5,6-pentafluorobenzhydrolby condensation of o-methoxyben-zaldehyde with pentafluorophenylmagnesium bromide in boiling ethyl ether for 2 h (96%). Then, this benzhydrol was oxidized with chromium trioxide in acetic acid at 20 for 20 h (95%) [570]. 

Pentafluorophenylmagnesium bromide reacts readily with mercury(II) chloride to give bis(pentafluorophenyl)mercury, which may be recrystallized from carbon tetrachloride as white crystals. The thermal stability of the mercurial is high a sample heated at 250° C for 5 hours in vacuo was unaffected. Apparently fluorine migration from the pentafluorophenyl group to mercury, thereby affording tetrafluorobenzyne, does not occur readily. Bis(pentafluorophenyl)mercury resists decomposition by protonic acids. It may be recrystallized from concentrated sulfuric acid. In carbon tetrachloride equimolar quantities of bromine and bis(pentafluorophenyl)-mercury at 60° C yield pentafluorophenylmercuric bromide and pentafluoro-bromobenzene. Bis(pentafluorophenyl)mercury is unusual in its ability to react with bipyridyl and with l,2-bis(diphenylphosphino)ethane to form... 

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