n-butyl-lithium in diethyl ether byproducts: lithium chloride; to cooled in ethanol-dry-ice bath BrPhC=CMe2 in ether n-butyl-lithium added dropwise with stirring and mixt. stirred at low temp. for 30 min and warmed slowly to room temp., soln. recooled to -78°C and SnCl4 added dropwise with stirring; mixt. allowed to warm to room temp. and stirred overnight, solvent removed under vac., residue refluxed in benzene, soln. filtered, solvent removed under vac., Et2O added to residue, mixt. filtered, ppt. recrystd. from benzene-hexane; elem. anal.;