Phenylmagnesium fluoride

The preparation of Grignard reagents at low temperatures, even the preparation of phenylmagnesium fluoride at — 20 °C, demonstrates the versatility of such developments. 

Full details of the preparation of alkylmagnesium fluorides are now available " (c/.Vol. 1, p. 87), and information on their structure and reactivity is also to hand. At last, phenylmagnesium fluoride has been prepared directly, albeit in poor yield the magnesium must be in the super-active form obtainable by alkali-metal reduction of anhydrous magnesium chloride or bromide in ether solvents. ... 

Interestingly, the first alkylmagnesium fluorides have been prepared in high yield by reaction of alkyl fluorides with magnesium in the presence of catalysts e.g. iodine) and by reaction of dialkylmagnesium compounds with boron trifluoride etherate both types of reaction are carried out in THF, and the latter can be applied to diphenylmagnesimn to provide phenylmagnesium fluoride. 

More conclusive evidence for the intermediacy of benzocyclopropenyl cations was obtained upon chloride/fluoride exchange of 22 with AgF in acetonitrile, which led to the chloro-fluoro derivative 278 and, ultimately, to the difluoro compound 279 in almost quantitative yield. Reaction of 22 with LiAlH AlClj afforded 2,5-diphenylbenzocyclopropene (264), while that with ethyl magnesium bromide lead to the diethyl derivative 280. Phenylmagnesium bromide and methylmagne-... 

With hydrohalic acids as catalysts, the hydrolysis of 1,3,2-dioxathiolane 2-oxide (16) is considered to occur (partly or entirely) via a halosulfite intermediate, e.g. (138 X = C1). The marked acceleration of the aqueous hydrolysis of catechol cyclic sulfite by small amounts of fluoride ion is likewise attributed to a nucleophilic catalysis (76CRV747). The nucleophilic attack of (16) at carbon by halide ion on reaction with phenylmagnesium bromide has already been discussed in Section 4.33.3.3.4. 

Fluorobenzene [5] A solution of phenylmagnesium bromide (from bromobenzene (1.57 g, 10 mmol) in ether (50 ml)) is added dropwise during 30 min to a stirred slurry of /V-fluoroquinuclidinium fluoride (1.49 g, 10 mmol) in ether (15 ml), under an inert atmosphere. An immediate reaction gives a fine white precipitate. The mixture is stirred for 2 h, filtered, and the filtrate added to chloroform, resulting in further precipitation. The mixture is filtered, and the filtrate is concentrated under reduced pressure, and filtered to remove solid quinuclidine. The filtrate is carefully concentrated and the residual liquid is carefully fractionally distilled to give fluorobenzene (0.249 g, 23%), b.p. 84°. 

Phenyl isocyanate, 322-323, 402, 427 Phenylisocyanide dichloride, 319 Phenyl isothiocyanate, 323 Phenylketene acetals, 340 Phenyllithium, 95, 96, 343, 386, 415 Phenylmagnesium bromide, 205 Phenylmaleonitrile, 21 Phenylmethanesulfonyl fluoride, 323 2-Phenyl-3-methyl-l,3,2-oxazophospholine, 323... 

Prsparation. The first preparation of VF dates back to 1901 and the reaction of zinc with l,l-difluoro-2-bromoethane [359-07-9] (3). Phenylmagnesium bromide in ether and potassiiun iodide solution can replace the metal for de-halogenation (4,5). Most approaches to VF s3uithesis have employed reactions of acetylene [74-86-2] with hydrogen fluoride (HF) either directly (5-8) or utilizing a catalyst (6,9-13) based on merciuy or aluminum (6,9,12,14). In another process, an acetylene/HF mixture is passed over a mercuric chloride or fluoride catalyst, which also produces vinyUdene fluoride and difluoroethane as by-products (10). Another S3uithesis (11) consists of two steps in which 1,1-difluoroethane (DFE) is... 

Synthetic Transformations of 2-Pyridyl-substituted Vinyl-silane. 2-Pyridyl-substituted vinylsilanes can be converted into other vinylsilanes. Subjection of 2-pyridyl-substituted vinylsi-lanes to potassium fluoride/methanol leads to the formation of methoxy(vinyl)silanes by pyridyl-silyl bond cleavage (eq 4). The resultant methoxysilanes can be further allowed to react with Grig-nard reagents such as phenylmagnesium bromide to give the corresponding vinylsilanes that are commonly used for various transformations (eq 4). ... 

Related Reagents. n-Butyllithium potassium fluoride phenylmagnesium bromide aluminum chloride bromine sodium methoxide. 

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