in tetrahydrofuran T=0°C; 4 h;

Yield given. Multistep reaction;

in hexane under N2; dropwise addn. of Sn(CH3)3Cl in hexane to a stirred suspension of K2(C4H6) in hexane, 1h; addn. of THF, stirring, 2h;; filtration of suspension through Kieselgur; dissoln. of residue in ethanol; extn. with hexane; concn. of combined hexane phases under reduced pressure; distn. of residue (51°C, about 10E-3bar);;