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Halomethyl-Metal Compounds. XLV. Organomercury CF,CCl Transfer Reagents: PhHgCCl,CF, and PhHgCC1BrCF,'92 Dietmar Seyferth* and David C. Mueller, Contribution f r o m the Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts Receified October 15, 1970
02139.
Abstract: The organomercury compounds PhHgCC12CF3and PhHgCClBrCF, have been prepared and evaluated as possible CF3CCI transfer reagents. The former is too stable, even at 160",to be a useful CF,CCI source. PhHgCCIBrCF, on the other hand, serves well in CF3CCItransfer reactions at 130-140" to olefins and to silicon hydrides. Thus the reaction of PhHgCClBrCF, with cyclooctene (138" for 5.5 days) gave a mixture of both isomers of 9-ch!oro-9-trifluoromethylbicyclo[6.1.O]nonanein 74 % yield, together with a small amount of 7-bromo7-trifluoromethylbicyc10[6.1.O]nonane (5 %). Reactions of this mercury reagent with cyclohexene, allyltrimethylsilane, tetramethylethylene, trimethylethylene, and cis- and rruns-2-butene also are described. Product instability at the high reaction temperatures can be a problem (e.g., the case of allyltrimethylsilane). Reaction of PhHgCCIBrCF, with triethylsilane (cu. 13O0, 6 days) gave Et3SiCHCICF3in 52% yield, while reaction of this mercurial with triphenylphosphine in the presence of benzaldehyde gave the expected PhCH=C(CI)CFs (38 %). Sodium iodide in 1,2-dimethoxyethanedisplaced the CF3CCIX- (X = C1 and Br) anions from PhHgCCI2CF3and PhHgCCIBrCF3,respectively. These lost fluoride ion to give CC12==CF2 and CCIBr=CF2, respectively. No CF3CCl transfer to cyclohexene occurred under these conditions.
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ur recent interest in organometallic routes to fluorine-containing carbenes4 (e.g., PhHgCC1,F + CClF,j PhHgCF3-NaI +.CF2,Gand Me3SnCF3-NaI + CF?) has prompted us to consider a similar method for the generation of trifluoromethyl-substituted carbenes. Various carbenes of this type have been described previously: CF3CH aia CF3CHN2,8CF3CCN uia CF3(CN)CN2,g (CF&C cia the diazoalkane and the diazirine.'O However, carbenes of type CF,CX (X = F, C1, Br) have not been described and it was to the generation of CF3CCl (or of a CF3CCl "carbenoid") that we decided to devote our attention. An organometallic reagent of type MCXClCF, (X = C1 or Br) would be required, and in view of our previous success with the application of phenyl(trihalomethy1)mercury compounds as dihalocarbene precursors, l 1 the mercury compounds PhHgCC12CF3 and PhHgCClBrCF, seemed the most promising. However, it was by no means clear that CF3CC1 extrusion from these compounds (eq la) would be the preferred mode of decomposition since a @elimination process (eq lb) also was possible. In this connection, it (1) Part XLIV:
D. Seyferth, R. Damrauer, S. B. A n d r e w , and
S. S. Washburne, J . Amer. Chem. SOC.,93, 3709 (1971).
(2) Preliminary commuiiicatioii: D. Seyferth, D. C. Mueller, and R. L. Lambert, Jr., ibid., 91, 1562 (1969). (3) National Science Foundation Graduate Fellow, 1967-1970. (4) D. Seyferth, Carbene Symposium sponsored by the Divisions of Fluorine Chemistry and Organic Chemistry, 160th National Meeting of the American Chemical Society, Chicago, Ill., Sept 14-19, 1970 (review paper). ( 5 ) D . Seyferth and I
