NEW SYNTHETIC METHODOLOGY FOR ORGANOFLUORINE COMPOUNDS. PART A: OLIGOMERIC PERFLUOROALKYL COPPER REAGENTS FROM REACTION OF COPPER METAL WITH DIFLUORODIHALOMETHANES. PART B: FLUORINE CONTAINING KETENE SILYL ACETALS AND THEIR ENOLATE CHEMISTR

Bromohalodifluoromethanes (CF$sb2$BrX where X = Cl or Br) were reacted with copper powder in DMF to give a mixture of perfluoroalkyl copper reagents.(UNFORMATTED TABLE OR EQUATION FOLLOWS)$$vbox{halign{hfil#hfilenspace&&enspacehfil#hfilenspacecr Cu + CF$sb2$BrX& ${rm DMFover >65spcirc Cquad}$& CF$sb3$(CF$sb2)sb{rm n}$Cucr (X = Cl, Br)&&(n = 1--14)cr}}$$(TABLE/EQUATION ENDS).;The mechanism involves formation of difluorocarbene and copper bromide, reaction of difluorocarbene with solvent to give fluoride ion, reaction of fluoride ion and difluorocarbene to produce trifluoromethyl anion, displacement of bromide on CuBr by trifluoromethyl anion to give trifluoromethyl copper and a series of carbene insertions to give a mixture of perfluoroalkyl copper reagents. When aryl iodides are added to the reaction of copper and difluorodihalomethane, perfluoroalkylated aromatics, including trifluoromethyl aromatic, are formed. A method to selectively produce trifluoromethyl aromatics was developed with this reaction. Thus, reaction of copper, CF$sb2$Br$sb2$ or CF$sb2$BrCl, KF or CsF, and aryl iodide in DMF gave trifluoromethyl aromatics in good yields.(UNFORMATTED TABLE OR EQUATION FOLLOWS)$${rm Cu + CFsb2BrX + MF + ArI enspace{DMFover 85spcirc Cquad}enspace CFsb3Ar}$$(TABLE/EQUATION ENDS).;Fluorinated analogues of the Reformatsky reagent were preformed. Although a stable mono fluoro zinc reagent (X = H) could not be formed, it was possible to utilize this in reactions by trapping it in situ. The difluoro zinc reagent was shown to have a carbon metallated structure.(UNFORMATTED TABLE OR EQUATION FOLLOWS)$$eqalign{{rm Zn(Hg) +}& {rm CFXBrCOsb2Et to YZnCFXCOsb2Et}cr &{rm (X = F, Cl, Br)}cr}$$(TABLE/EQUATION ENDS).;The zinc reagents underwent copper(I) catalyzed acylation to give $beta$-ketoesters with fluorinated acid chlorides and oxygen acylated products with non-fluorinated acid chlorides. When zinc was reacted with fluorosubstituted bromoacetic esters in the presence of trimethylchlorosilane, fluoroketene silyl acetals were formed in good yields. Both E and Z isomers of the ketene silyl acetals were produced.(UNFORMATTED TABLE OR EQUATION FOLLOWS)$$vbox{halign{enspace#hfil&&enspace#hfilcr &&&OSiMe$sb3$cr Zn(Hg) +& CFXBrCO$sb2$& + Me$sb3$SiCl $to$ FXC=Ccr &(X = H, F, Cl, Br)&&OEtcr}}$$(TABLE/EQUATION ENDS).;Their spectral assignments were made on the basis of nuclear overhauser enhancement spectroscopy and the observance of long range through space hydrogen-fluorine coupling. These ketene silyl acetals underwent a variety of reactions including acylation with both fluorinated and nonfluorinated acid chlorides to give $beta$-ketoesters in good yields.(UNFORMATTED TABLE OR EQUATION FOLLOWS)$$vbox{halign{enspace#hfil&&enspace#hfilcr &OSiMe$sb3$& quadenspace O&& enspaceenspace Ocr CFX=C&& + RCCl& $to$& RCCFXCO$sb2$Etcr &OEtcr}}$$(TABLE/EQUATION ENDS).