n-butyllithium in diethyl ether; hexane at -78°C to soln. of furan (ether) soln. of C4H9Li (C6H14) added,soln. stirred (N2, -78°C, 1 h; 3 h, 20°C), cooled (-78.de gree.C), Sn(CH3)3Cl in ether added dropwise via a siringe, stirred (2 h,-78°C; overnight, room temp.); mixt. quenched with aq. NH4Cl, extd. with ether (twice), ether layers dried (Na2SO4), concd. (vac.), residue distilled;

methyllithium; ammonium chloride; methyl iodide in tetrahydrofuran under N2; to a soln. of the starting bisstannyl-compd. in THF is added dropwise MeLi at -78°C, after 2 h MeI is added; after 2 h quenched with satd. NH4Cl, extd., the combined organic extracts are dried, the solvents are removed, elem. anal.;