in dichloromethane byproducts: CH4; excess SnMe4 (ca. 30 equiv.) added to soln. of Pd complex in CH2Cl2; react. mixt. stirred at room temp. for 15 h; soln. evapd.; redissolved in CH2Cl2, filtered over Celite; solvent evapd.; recrystd. from CH2Cl2 at -20°C; elem. anal.;