water in diethyl ether; dichloromethane under N2; to excess of H2O in Et2O added cooled (0 °C) soln. of B complex in CH2Cl2 with stirring, stirred for 10 min; water layer sepd., org. layer washed with cold H2O and brine, dried with MgSO4, evapd. in vac., recrystd. from C6H6;