sodium amalgam in toluene under inert atm. chlorocatecholborane was dissolved in toluene, Na/Hg amalgam was added and heated at 90°C under N2 for 3 h; soln. was filtered and evapd.;

sodium amalgam in toluene under N2 atm. to soln. catechol in toluene at 0°C BBr3 was added dropwise, stirred at 0°C for 0.5 h and allowed to warm to room temp., Na/Hg amalgam was added and heated at 90°C under N2 for 5 h; soln. was filtered and evapd., residue was recrystd. from toluene/pentane at -35°C;

in diethyl ether N2-atmosphere; addn. of 2 equiv. substituted catechol to B-compd. at 0°C; dropwise addn. of excess 1 M HCl in Et2O, stirring at 0°C overnight, extn. into PhMe, filtration (Celite), concn., crystn. (-30°C,24 h), collection, washing (hexanes), drying (vac.); elem. anal.;