1: 3-bromo-N-(diphenylmethylene)aniline With n-butyllithium in tetrahydrofuran; hexane T=-78°C; 1 h; 2: boric acid trimethyl ester in tetrahydrofuran; hexane T=-85°C; 1 h; 3: 2,3-dimethylbutane-2,3-diol With sodium hydroxide; sulfuric acid Product distribution / selectivity; more than 3 stages;