Fluor substitution

The fate of the intermediate cation and the deprotonation step are clearly dictated by the electronic requirements of the fluor-substituted carbon atoms. 

The high reactivity of N-H bonds has also been exploited to produce N-F denvatives without significant substitution on neighbonng C-H bonds, Diethyl-phosphoramidates of ammonia, alkylammes, and a,polar solvents to produce difluoroamine [57], N,N-difluoroalkylamines, and a,to-bis(At,7V-difluoroamino)alkanes [52] Acetamide undergoes fluonnation to give modest yields of N,N difluoroacetatnide and acetyl fluonde when fluorinated... 

As noted, these zinc reagents find extensive application in the preparation of fluorinated styrenes [113, 114], aryl-substituted fluorinated propenes [114],fluor-inateddienes [115,116], and tnfluorovinyl ketones [117], as illustrated in equations 83-88... 

Dialkylaminosulfur trifluorides are widely used as a safe substitute for SF4 in the replacement of oxygen by fluorine in many types of organic compounds, for example, converting alcohols to fluorides, or aldehydes and ketones to gem-difluorides. The most familiar of these reagents is DAST, while an increasingly popular one (considered safer to use than DAST) is bis(2-methoxyethyl)aminosulfur trifluoride (Deoxo-Fluor Reagent) (Scheme 7.15). 

A direct catalytic conversion of esters, lactones, and carboxylic acids to oxazolines was efficiently achieved by treatment with amino alcohols in the presence of the tetranuclear zinc cluster Zn4(0C0CF3)60 as catalyst, essential for condensation and cyclodehydration reactions. For example, the use of (5)-valinol allowed the easy synthesis of oxazolines 125 and 126 in satisfactory yields <06CC2711>. A one-pot direct preparation of various 2-substituted oxazolines (as well as benzoxazoles and oxadiazoles) was also performed from carboxylic acids and amino alcohols (or aminophenols or benzhydrazide) using Deoxo-Fluor reagent <06TL6497>. 

Ryabukhin SV, Plaskon AS, Ostapchuk EN, Volochnyuk DM, Shishkin OV, Tolmachev AA (2008) CF3-substituted 1,3-dicarbonyl compounds in the Biginelli reaction promoted by chlorotrimethylsilane. J Fluor Chem 129 625-631... 

G. Angelini, M. Speranza, A.P. Wolf, C.Y. Shiue, Nucleophilic aromatic-substitution of activated cationic groups by F-18-labeled fluoride—A useful route to no-carrier-added (nca) F-18-labeled aryl fluorides, J. Fluor. Chem. 27 (1985) 177-191. 

For the correct interpretation of the luminescent bands, artificial apatite standards have been investigated, as nominally pure, as activated by different potential luminogen impurities. Natural carbonate-fluor-apatites not containing REE were heated with 1 - 5 wt. % of oxides of Eu, Pr, Sm and Dy at 900 °C in air and in vacuum. By changing the activation conditions the differentiation between isomorphous substitutions in different Ca-sites has been achieved. Under vacuum the compensation of the excessive positive charge by substitution of E by 0 is impossible and the luminescence centers in Ca(ll) sites may be less preferential. After heating at this temperature carbonate-fluor-apatite loses its carbonate content and becomes very similar to natural fluor-apatite. 

Unsubstituierte Imidazole reagieren wie zahlreiche andere Nukleophile mit elektronenarmen Halogen-arenen unter nukleophiler Substitution des Halogen-Atoms zu 1 -Aryl-imidazolen. So wird z.B. aus Imidazol mit 4-Fluor-l,3-dinitro-benzol/ Dimethylformamid bei 20° in 91% Ausbeute l-(2,4-Dirtitro-phenyI)-imidazol erhalten769. 

Aus 2,4(5)-Difluor-5(4)-ethoxycarbonyl-imidazol erhalt man durch selektive Substitution des Fluor-Atoms in 2-StelIung mit Ammoniak in Methanol 2-Amino-5(4)-ethoxycarbonyl-4(5)-fluor-imidazol in 65% Ausbeute928. 

Difluor-nitro-benzole werden von Natrium-methanthiolat unter Erhalt der Nitro-Gruppe substituiert. 3-Fluor-l-nitrobenzol verhalt sich anders anstelle der Substitution tritt Kon-densation zu Bis- 3-fluor-phenyI -diazen-l-oxid (12%) ein1 ... 

Die Ringoffnung von Azirinen mit Fluorwasserstoff/ Pyridin verlauft je nach Substitution und Bedingungen unterschiedlich2,5> 6 unter Bildung von Pyrazinen, a-Fluor-ketonen und/oder 2,2-Difluor-alkylaminen. So erhalt man z.B. aus 2-Methyl-3-phenyl-2H-azirin 2-Amino-1,1-difluor-l-phenyl-propan als Hauptprodukt5. 

Dimethyl- and l,3-dimethyl-5-halo-substituted uracil derivatives react with cesium fluor-oxysulfate under mild reaction conditions. The reaction carried out in an acetonitrile/water mixture or in an alcohol (methanol, ethanol, propan-2-ol or /a7-butyl alcohol) results in the regioselective formation of 5-fluoro-6-hydroxy- or 6-alkoxy-5-lluoro-l, 3-dimethyl-5,6-dihydro-uracil derivatives 27, respectively, while the stereochemistry of the reaction is strongly syn predominant.29... 

Miller, W. T. Fried, J. H. Goldwhite, H. Substitution and addition reactions of the fluoroo-lefins. IV. Reactions of fluoride ion with fluor-oolefins./. Am. Chem. Soc. 1960, 82, 3091-3099. 

Als Substituent zweiter Ordnung ermoglicht der Diphenylphosphoryl-Rest in para-Posi-tion die nukleophile Aromaten-Substitution, Aus Diphenyl-(4-fluor-phenyl)-phosphano-xid und Kaliumcyanid laBt sich so (4-Cyan-phenyl)-diphenyl-phosphanoxid in quantita-tiver Ausbeute herstellen396 ... 

Alkorta I, Rozas I, Elguero J (2000) Effects of fluorine substitution on hydrogen bond interactions. J Fluor Chem 101 233-238... 

A medium-polarity stationary phase based on fluor-alkyl-phenyl substitution, which is thermally stable up to 400°C, was reported [12], and a CHjO-terminated polydimethyl sUoxane, diphenyl-substituted stationary phase made possible the analysis of complex high-molecular-mass mixtures such as free-base porphyrins and triglycerides using narrow-bore capillary columns 2 [5]. Since these developments, a variety of stationary... 

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