Fluonnated reagents

In the past 20 years, the appUcatton of fluonnated reagents m chemistry experienced tremendous growth Some well known denvatives of hydrofluoric acid and tri-fluoroacetic acid found new applications, and many new classes of synthetically useful fluorinated organic and inorganic compounds have been synthesized... 

Elemental Huonne as a Legitimate Reagent for Selective Fluonnation of Orgamc Compounds Fluoroaromatic Compounds Synthesis, Reactions, and Commercial Applications New Aspects of Carbonylations Catalyzed by Transition Metal Complexes Polyfluoroaromatics An Excursion m Carbamon Chemistry ... 

A variety of reagent combinations add fluorine and sulfur to fluonnated olefins. Typically the olefin is reacted with fluoride ion and a source of electrophilic sulfur, such as sulfur tetrafluonde[757,178,179, 7S0], alkyl or amino sulfur tnfluondes [757, 787],... 

The product from fluonnation of sodium acetate is acetyl hypofluorite [64], which IS isolated and characterized [65] The value of this reagent lies in its relative mildness, because it reacts cleanly with most olefins adding the elements of acetoxyl and fluorine [66] Tnfluoroacetyl hypofluorite adds cleanly only to benzylic or electron-rich double bonds... 

Systems usually fluonnated by electropositive fluorine reagents include acti-vated alkenes (enol ethers, enol acetates, silyl enol ethers, and enamines), activated aromatic systems, certain slightly activated carbon-hydrogen bonds, and selected organometallics. 

Polynuclear aromatics react with fluoroxy reagents to give high yields of ortho substitution products accompanied by varying yields of geminal difluoro products Thegeminal difluonnation occurs presumably by an addition-elimination mechanism [27 28, 29, 30, 31, 32] Unactivated aromatic systems are fluorinated in lower yield to give monofluonnated products (Table 1, entries 6 and 7) Examples of fluonnation of polynuclear systems [/5, 21, 25, 30, 32, 7 ] are shown m equations 7-10... 

Fluorine is well known for its ability to fluonnate seleeti vely terttary carbon-h drogen bonds that are slightly activated by polar substituents Hypofluorite reagents also react with carbon-hydrogen bonds, both secondary and tertiary but tertiary bonds react better [6]... 

The preparation of aromatic fluorine compounds may be accomplished by direct fluorination or by fluonnation of organometallic intermediates. Tlte ipso fluorination of an aryl organometallic derivative with a positive fluorine reagent allows control over the regioselectivity of the fluorination and offers advantages in the preparation of F-labeled materials [II, 50],... 

The fluorination of organometallics with Al-fluoroamide reagents has received Only limited attention. Grignard reagents, both aliphatic and aromatic, are converted to organofluonne compounds. Both the electron transfer and the Sf,j2 ntechamsms have been considered in these processes [SO, 81, 82], The reactions 0 exemplified in equation 46 [48, 69, 70, 71, 75] Organosilanes are also fluonnated [71] (equation 47)... 

Xenon difluoride may be used as the pure reagent or as a graphi te intercalate for the effective fluonnation of polynuclear aromatics [86 87] (equations 49 and 50)... 

Perchloryl fluoride, well known for its ability to fluonnate organic substrates, has become a reagent with limited appeal. Its loss of popularity stems from difficult... 

Reactions of polyhydroxyl compounds such as carbohydrates with DAST lead to replacement of one or two hydroxyl groups by fluorine, more fluorine atoms are not introduced even when a large excess of the reagent is used [132, 139, 147] Although diethylaminosulfur tnfluonde (DAST) is the most popular, other dialkylaminosulfuranes, such as diisopropylamino- [95] pyrrolidino [95 109 /27], dimethylamino- [148], piperidino- [148] and particularly morpholinosulfur trifluonde [148,149, ISO], are also used as fluonnating agents to convert alcohols into fluorides... 

Acylation of various oxygen functions by use of common and commercially available fluonnated carboxylic acid denvatives such as trifluoroacetic anhydride or the corresponding acyl halides have already been discussed sufficiently in the first edition [10] Therefore only exceptional observations will be described in this section In the past 15 years, many denvatizations of various nonfluonnated oxygen compounds by fluoroacylation were made for analytical purposes. Thus Mosher s acid chlorides for example became ready-to-use reagents for the determination of the enantiomeric purity of alcohols and amines by NMR or gas-liquid chromatographic (GLC) techniques [//] (equation 1)... 

Fluoroolefins may he prepared by the reaction of Wittig reagents and other pho sphorus-containtng y tides with fluorinated carbonyl compounds. (A discussion of the fluorinated Wittig reagents or other fluonnated phosphorus reagents with nonfluorinated carbonyl compounds is on page 581.) Tnphenylphosphoranes, derived from alkyltriphenyl phosphonium salts, react with 1,1,1-trifluoroacetone [3/] or other trifluoromethyl ketones [32, iJ] (equation 26) (Table 10). 

Reductive coupling reaction of fluonnated vinyl iodides or bromides has been used as a route to fluorinated dienes [246, 247, 248, 249, 250. Generally, the vinyl iodide is heated with copper metal in DMSO or DMF no 1 ntermediate perfluorovmy I-copper reagent is detected. Typical examples are shown m equations 163-165 [246, 247, 249. The X-ray crystal structure of perfluorotetracyclobutacyclooctatetraene, prepared via coupling of tetrafluoro-l,2-diiodocyclobutene with copper, is planar... 

The nucleophilic attack of nitrogen bases leads to a variety of products as the result of addition or addition-elimination reactions The regioselectivity resembles that of attack by alcohols and alkoxides an intermediate carbanion is believed to be involved In the absence of protic reagents, the fluorocarbanion generated by the addition of sodium azide to polyfluonnated olefins can be captured by carbon dioxide or esters of fluonnated acids [J 2, 3] (equation I)... 

Nitrones are among the most highly studied and useful reagents for the synthesis of five-membered-nng heterocycles. The first fluonnated nitrone, N-methyl-C-(trifluoromethyl)nitrone, was prepared recently and used to introduce Irifluoromethyl groups into such heterocycles... 

With highly fluorinated compounds, even relatively weak bases cause elimination of hydrogen fluoride Such reagents are especially desnable in dehydro-fluonnations of polyfluoro compounds containing functionalities that would suffer from stronger bases [21 (equation 19)... 

Covalent fluondes of group 3 and group 5 elements (boron, tin, phosphorus, antimony, etc ) are widely used m organic synthesis as strong Lewis acids Boron trifluoride etherate is one of the most common reagents used to catalyze many organic reactions. A representative example is its recent application as a catalyst in the cycloadditions of 2-aza-l,3-dienes with different dienophiles [14] Boron trifluoride etherate and other fluonnated Lewis acids are effective activators of the... 

One-carbon fluonnated compounds are used as synthetic reagents and in many theoretical inquines of structure and spectroscopy Twenty fluorohalomethanes are listed in Table 1 [56, 57, 58 59, 60, 61, 62] Fluorocarbons llBl, 22B1, and 31B1 and 12 of 15 lodofluoromethanes are not listed because of a lack of NMR data Most of the if-F values are taken from the older literature [57, 59], obtained from... 

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