- Synthesis of 3-fluoromethyl-2,1-benzisoxazoles
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A convenient synthetic method to access hitherto unknown 3-(trifluoromethyl)- and 3-(difluoromethyl)-2,1-benzisoxazoles by the reaction of sodium azide with 1-(2-halophenyl)-2,2,2-trifluoroethanones or 1-(2-halophenyl)-2,2-difluoroethanones was developed. 3-Fluoromethyl-2,1-benzisoxazoles are versatile precursors for o-fluoroacetylanilines.
- Golubev,Shidlovskii,Peregudov,Kagramanov
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p. 2264 - 2270
(2015/06/22)
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- Oxidation of α-trifluoromethyl alcohols using a recyclable oxoammonium salt
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A simple, mild method for the oxidation of α-trifluoromethyl alcohols to trifluoromethyl ketones (TFMKs) using the oxoammonium salt 4-acetylamino-2,2,6,6-tetramethylpiperidine-1-oxoammonium tetrafluoroborate (1) is described. Under basic conditions, oxidation proceeds rapidly and affords good to excellent yields of TFMKs, without concomitant formation of the hydrate. The byproduct of the oxidation, 4-acetylamino-2,2,6,6-tetramethyl-1- piperidinyloxy (1c), is easily recovered and can be conveniently reoxidized to regenerate the oxoammonium salt.
- Kelly, Christopher B.,Mercadante, Michael A.,Hamlin, Trevor A.,Fletcher, Madison H.,Leadbeater, Nicholas E.
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p. 8131 - 8141
(2013/01/15)
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- Silver compounds in synthetic chemistry. Part 5: Selective syntheses of trifluoromethylketones, RCOCF3, from trifluoromethylsilver, AgCF3, and corresponding acyl chlorides, RCOCl
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Trifluoromethylketones of aromatics, heteroaromatics and olefins are formed selectively from reactions of trifluoromethylsilver and the corresponding carboxylic acid chlorides in moderate to excellent yields. The conditions chosen are dependent on the nature of the acyl chloride. Attempts to prepare alkyl(trifluoromethyl)ketones yielded product mixtures of the corresponding acyl fluorides, trifluoromethyl-, pentafluoroethyl- and n-heptafluoropropyl ketones.
- Kremlev, Mikhail M.,Mushta, Aleksej I.,Tyrra, Wieland,Naumann, Dieter,Fischer, Hendrik T.M.,Yagupolskii, Yurii L.
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p. 1385 - 1389
(2008/09/18)
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- The "tert-amino effect" in heterocyclic chemistry: synthesis of 3,1-benzoxazines and 3,1-benzothiazines
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Two different routes are described for the synthesis of the 2,2,2-trifluoro-1-ethanones 2 and 9 and their hydrates 3 and 10, respectively, via trifluoroacetylation of the N,N-dialkylanilines 1 and via a Barbier reaction of 2-fluorobenzaldehyde.These compounds were thermally converted into a mixture of cis- and trans-pyrrolo- and pyridobenzoxazines, (11: cis, 12: trans).The structure of these compounds was proven by X-ray analysis (11a) and 1H NOE difference spectroscopy.Cyclization of (R)-9b (R1 = CH3) gave predominantly one enantiomer (12f, 70percent) and in addition two diastereomers of 17a and two of 18a (total yield ca. 17percent), while cyclization of (S)-9c (R1 = CH2OCH3) gave a mixture of 12g (18percent), two diastereomers of 17b (36percent) and two diastereomers of 18b (18percent).The benzaldehyde 19a (R3 = H), acetophenone 19d (R3 = CH3), trifluoroacetophenones 19b,c (R3 = CF3) and benzophenone 19e (R3 = C6H5) reacted with Lawesson's reagent to yield exclusively the trans-pyrrolobenzothiazines 21a-e in yields of 33-77percent.Reaction of 19f (R1 = CH3, R3 = H), 19g (R1 = CH3, R3 = CF3) and 19h (R1 = CH3, R3 = CH3) with Lawesson's reagent resulted in the formation of mixtures of isomers 21-24.
- Nijhuis, W. H. N.,Verboom, W.,Harkema, S.,Reinhoudt, D. N.
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p. 147 - 160
(2007/10/02)
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