in tetrahydrofuran; ethanol under N2; mixt. of B compd. and CsF (molar ratio 1:4.7) in EtOH-THF stirred under reflux for 27 h; cooled to room temp.; filtered (first crop); solvent removed from filtrate; dissolved in acetone; filtered; washed with acetone; filtrate dried (second crop); combined solid washed with CH2Cl2; recrystd. from acetone-Et2O;

in tetrahydrofuran; ethanol under N2; mixt. of B compd. and CsF (molar ratio 1:4.7) in EtOH-THF stirred under reflux for 27 h; cooled to room temp.; filtered (first crop); solvent removed from filtrate; dissolved in acetone; filtered; washed with acetone; filtrate dried (second crop); combined solid washed with CH2Cl2; recrystd. from acetone-Et2O;