in dichloromethane under N2, stirred for 20 h at room temp.; filtered (NaBF4), solvent volume reduced in vac., dropwise addn. of diethyl ether, pptn. recrystd. (CH2Cl2/Et2O); elem. anal.;

in dichloromethane under N2, stirred for 20 h; filtered (NaBF4), solvent volume reduced in vac., dropwise addn. of diethyl ether, pptn. recrystd. (CH2Cl2/Et2O); elem. anal.;