in tetrahydrofuran byproducts: C2H4, CH2CHCH3, C2H6; Ar atmosphere, treatment of solns of educts (over 45 min, gas evolution), stirring (25°C, 18 h), volatiles removal; stirring of residue with THF (12 h), washing (THF, pentane), drying (high vacuum); elem. anal.;

magnesium; mercury dibromide 1.) ether, 2.) THF, 24 h; Multistep reaction;