- A general facile preparation of F-alkylacetylenes
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F-Alkylethylenes can be exhaustively chlorinated under UV irradiation to give F-alkylpentachloroethanes in high yields. Subsequent dechlorination with three equivalents of zinc readily gives the F-alkylacetylenic zinc reagents, which on hydrolysis with aqueous HCl provide the corresponding F-alkylacetylenes in good yields. The methodology is applicable to F-alkyl groups of various chain lengths, and the F-acetylenic zinc reagent produced as the reaction intermediate can also be utilized in the direct preparation of functionalized F-alkylacetylenes.
- Burton, Donald J.,Spawn, Terence D.
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- Reactions of fluoroalk-1-en-1-yltrifluoroborate and perfluoroalk-1-yn-1- yltrifluoroborate salts and selected hydrocarbon analogues with hydrogen fluoride and with halogenating agents in aHF and in basic solvents
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The relative rate of the electrophilic hydrodeboration of K[R′BF 3] with HF (27-100%) diminishes in the series R′ = C 4H9CC > C4F9CFCFCC > CF 2C(CF3) > C3F7CC ～ (CF 3)2CFCC > CF3CC. When R′ = CF 3CC the new salt K[CF3CH2-CF2BF 3] was obtained by addition of HF besides CF3CCH and K[BF4]. Small amounts of water caused the formation of K[CF 3CH2-C(O)BF3] as a by-product. The electrophilic halofluorination of perfluoroalkenyltrifluoroborate salts with NCS or NBS in aHF (anhydrous HF) led to K[RFCFHal-CF2BF 3] (from K[RFCFCFBF3]) and K[R FCHal2-CF2BF3] (from K[R FCHalCFBF3] and K[RFCCBF3]) (Hal = Cl, Br). Treatment of K[RFCFCFBF3] and K[R FCCBF3] with 5% F2/N2 in MeCN gave the corresponding salts K[RFCF2-CF2BF 3] in 16-25% isolated yield. Reactions of K[trans-C4F 9CFCFBF3] with Cl2 in MeOH resulted in K[C 4F9CFCl-C(O)BF3] (major product). The latter was also obtained in reactions of K[trans-C4F9CFCFBF 3] with Cl2 in MeCN or sulfolane after sequential methanolysis of the primarily formed products. In contrast, the salts K[RCFCFBF3] (R = CnF2n+1, trans-C 4H9) and K[CF3CCBF3] underwent bromodeboration to RCFCFBr and CF3CCBr, respectively, when they were reacted with bromine in the polar solvents MeOH, MeCN, or sulfolane.
- Bardin, Vadim V.,Adonin, Nicolay Yu.,Frohn, Hermann-Josef
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experimental part
p. 114 - 128
(2012/04/10)
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- SYNTHESIS OF FLUORINATED α-DIKETONES AND SOME INTERMEDIATES
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Reactions of perfluoroalkylcopper compounds with α-ketoacyl chlorides were used for the synthesis of fluorinated α-diketones.Heptafluoropropylcopper prepared from copper bronze and 1-iodoheptafluoropropane reacted with benzoylformyl chloride to give heptafluoro-1-phenyl-1,2-pentanedione, with trimethylpyruvyl chloride to give 2,2-dimethyl-5,5,6,6,7,7,7-heptafluoro-3,4-heptanedione, and with 3,3,4,4,5,5,5-heptafluoro-2-keto-pentanoyl chloride or oxalyl chloride to give tetradecafluoro-4,5-octane-dione.Syntheses of fluorinated acetylenes, cyanohydrins, α-hydroxy acids, α-keto acids, their chlorides, and other intermediates for the syntheses of α-diketones by the above route and by other methods are described.An interesting seven-membered ring containing β-hydroxy ketone was obtained by an intramolecular aldol condensation of a fluorinated bis(methyl) ketone.
- Hudlicky, M.
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p. 383 - 406
(2007/10/02)
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