Trifluoromethyl compounds from mercury compound

Other e. amples of [2+1] cycloaddition reactions with trifluoromethyl-substituted carbenes are known with carbenes bearing a halogen or a metho.xy substituent, which seems to result in a push-puir stabilization. Yields depend on the mode of generation of the carbenes best yields of eyclopropanes are obtained with carbenes generated from (polyfluorocthyl)mercury compounds. " ... 

A second, more indirect result of these studies is that for the first time large amounts, —10 g, of each of the bis(trifluoromethyl)Group IIB compounds became readily available. Bis(trifluoromethyl)mer-cury, for example, in addition to the syntheses indicated previously (1, 40), can also be conveniently prepared by any of a number of alternative methods, ranging from the direct fluorination of (CH3)2Hg to the reaction of mercury halides with CF3 radicals (99). The other disubsti-tuted compounds of Group IIB, (CF3)2Cd L2 and (CF3)2Zn L2, can be easily prepared from (CF3)2Hg as described below (100, 101). 

Treatment of the title compound with an aqueous base under phase-transfer catalysis conditions generates, by a-elimination, chloro(trifluoromethyl)carbene that can be trapped by cycloaddition to allylsilane and allylstannane derivatives, e.g. formation of 1 and 2. This method represents a fast and mild alternative to the Seyferth method that starts from the same alkyl halide and generates the carbene by thermal decomposition of l-bromo-l,2,2,2-tetra-fluoroethyl(phenyl)mercury (see Section 1.2.1.2.4.1.1). 

Tetrakis(trifluoromethyl)diarsine can also be obtained by reduction of the compounds (CF3)2AsX (X = Cl, I, Sj) with mercury at 20° C (30, 71, 178). Tetraaryldiarsines are available from similar reactions (305), although the most convenient method of preparing these compounds is by reducing the corresponding oxides or hydroxides with hypophosphorous acid (3). 

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