Multistep reaction;

in tetrahydrofuran N2; pinacol added at room temp. to a soln. of B-compound, stirred for 3h; solvent evapd.; distilled; elem. anal.;

water; silica gel in dichloromethane N2, water added to suspended silica gel in CH2Cl2, stirred until homogenous, B-compound added at room temp., stirred for 4.5 h; silica gel filtered off and washed (CH2Cl2); solvent removed; distd.; elem. anal.;