in tetrahydrofuran; cyclohexane (Ar), PhLi in cyclohexane added at -80°C to a THF soln. of Sn complex, warmed to room temp. over 3.5 h; evapd., filtered, chromy.(SiO2 - hexane/ethyl acetate 10:1);

in tetrahydrofuran; diethyl ether (Ar), 3 equiv. of MeLi in Et2O added at -90°C to Sn complex in THF, warmed to room temp.; evapd.;