1: [Rh(COD)Cl]2 With silver tetrafluoroborate in dichloromethane; acetone T=20°C; 1 h; 2: hydroquinone in dichloromethane; acetone T=20°C; 2 h;

1: silver tetrafluoroborate; [RhCl(η2:η2-cycloocta-1,5-diene)]2 in dichloromethane; acetone T=20°C; 1 h; 2: hydroquinone in dichloromethane; acetone T=20°C; 2 h;

in diethyl ether HBF4*Et2O added to soln. of complex and hydroquinone (Ar), stirred (1 h); react. soln. removed, redissolved in CH2Cl2, Et2O added (pptn.); elem. anal.;