62098-05-9Relevant academic research and scientific papers
Alkynylhalocarbenes 4. Generation of (alk-1-ynyl)halocarbenes from 3-substituted 1,1,1,3-tetrahalopropanes under the action of bases
Shavrin,Gvozdev,Nefedov
, p. 1237 - 1253 (2007/10/03)
When treated with KOH under phase-transfer catalysis or with Bu tOK, 3-substituted (alkyl or phenyl) 1,1,3-tribromo-1-fluoropropanes 1a-c exclusively generate previously unknown (alk-1-ynyl)fluorocarbenes 5a-c, which react with olefins to give 1-(alk-1-ynyl)-1-fluorocyclopropanes 6a-h in 12-69% yields. Under analogous conditions, 3-alkyl- and 3-aryl-3-bromo-1,1,1-trichloropropanes 2a-c selectively afford (alk-1-ynyl)chlorocarbenes 7a-c, which are trapped by olefins to form the corresponding 1-(alk-1-ynyl)-1-chlorocyclopropanes 8a-k in 35-70% yields. (Phenylethynyl)chlorocarbene 7a is also selectively generated from 1,1,1,3-tetrachloro-3-phenylpropane (3a) upon its treatment with Bu tOK. With an excess of 2,3-dimethylbut-2-ene or 2-methylpropene, carbene 7a yields 1-chloro-1-(phenylethynyl)cyclopropanes 8a or 8c, respectively. In contrast, 1,1,1,3-tetrachloroheptane 3b and 3-alkyl- and 3-phenyl-1,1,1,3-tetrabromopropanes 4a,c,f react with bases in the presence of olefins to give, along with the corresponding 1-(alk-1-ynyl) -1-halocyclopropanes 8a,c,d and 11a-f, vinylidenecyclopropanes 12a,c-g, which suggests the generation, under these conditions, both (alk-1-ynyl)halocarbenes 7b and 9a-c and vinylidenecarbenes 10 and 11a-c. The composition and structures of intermediate products in the reactions of tetrahalides 1b, 2a, 2b, 3a, and 3b with ButOK were determined and the mechanisms for carbene generation in these reactions were proposed.
REACTION OF BENZENESELENOL WITH TRI- AND TETRACHLOROETHYLENES UNDER CONDITIONS OF PHASE-TRANSFER CATALYSIS
Martynov, A. V.,Mirskova, A. N.,Kalikhman, I. D.,Voronkov, M. G.
, p. 454 - 462 (2007/10/02)
The reaction of benzeneselenol with trichloroethylene in concentrated sodium hydroxide solution, catalyzed by ammonium salts, leads to Z-phenyl α,β-dichlorovinyl selenide with an equimolar ratio of the catalyst and the selenol or to a mixture of the Z and E isomers with a ratio of 1:10.In addition to the expected trichlorovinyl selenide PhSeCCl=CCl2, the analogous reaction with tetrachloroethylene also gives a mixture of the Z and E isomers of α,β-dichlorovinyl selenides and, in addition, 1,2-bis(phenylseleno)-1,2-dichloroethylene PhSeCCl=CClSePh.If trialkylbenzylammonium chlorides R3PhCH2N(1+)*Cl(1-) are used as catalyst, phenyl benzyl selenide PhSeCH2Ph is formed as a side product.The results of the reaction in the case of trichloroethylene are explained by the addition of the selenolate ion to the CClCCl, generated from the trichloroethylene in situ, and isomerization of the initially formed Z-phenyl α,β-dichlorovinyl selenide to the thermodynamically more stable E isomer.In the case of tetrachloroethylene they are explained by the usual addition-elimination mechanism with the formation of trichlorovinyl selenide, accompanied by reductive dechlorination of the CCl2=CCl2 to CHCl=CCl2 by the selenolate and subsequent reaction of the selenolate with CHCl=CCl2.
