LiN(H)C6H2(CH3)3 in diethyl ether protective gas: nitrogen; dropwise addn. of dimesitylboronfluoride in etheric soln. to stirred (1 h) soln. of LiN(H)HC6H2(CH3)3 (in situ from mesidine and n-BuLi in Et2O/0°C); stirring of yellow soln. (12 h);; evapn.; residue dissolved in toluene; filtration; concn. (vac.); cooling (-20°C/12 h);;