Halomethyl-metal compounds : LIX. An Improved preparation of phenyl(fluorodichloromethyl)mercury, a useful fluorochlorocarbene precursor

Abstract

An improved procedure for the preparation of phenyl(fluorodichloromethyl)mercury involving the reaction of phenylmercuric chloride with sodium methoxide and fluorodichloromethane in THF/methanol at −40° is described. This procedure gives PhHgCCl 2F in high yield and generally of about 85% purity. Reactions of the PhHgCCl 2F thus prepared with olefins [cyclohexene, cyclooctene, allyltrimethylsilane, vinyltriethylsilane, Me 2CCHCl, Me 2CC(Br)Me, CH 2C(Me)CH 2Cl and norbornene] gave the expected cyclopropanes in high yield. This mercury reagent added CClF to the CN bond of PhNCCl 2, giving 1-phenyl-2-fluoro-2,3,3-trichloroaziridine and to the CS bond of thiobenzophenone. The thiirane formed was, however, unstable to the reaction and work-up conditions and only its desulfurization product, Ph 2CCClF, could be isolated. Fluorochlorocarbene transfer from this mercurial also could be induced by the action of sodium iodide in DME. Evidence is presented which shows that PhHgCCl 2F is more reactive in CClF transfer than indicated in a previous report.