carbon disulfide; lithium in tetrahydrofuran; 1,4-dioxane reaction of Ph3SnCl with Li in THF, sepg. of the excess of Li, addn. of CS2 in dioxane over 30 min, chromy. on silicagel (THF/ether), addn. of Ph3SnCH2Cl, stirring for 30 min, all steps under Ar; evapn. of the solvent, chromy. on silicagel (ether), recrystn. (acetone,n-hexane), elem. anal.;