A solution of 8.31 g (21.73 mmol) of 3,7-dimethoxy-4-(2-methoxy-ethoxymethoxymethyl)-10-methyl-phenothiazine in 100 ml of diethyl ether/tetrahydrofuran (4:1) was reacted with 17.6 ml of n-butyllithium solution (1.6M in hexane) and 3.68 g (32.6 mmol) of N-formylpiperidine analogously to that described in Example 4.1.1.c. The resulting 3,7-dimethoxy-6-(2-methoxyethoxymethoxymethyl)-10-methylphenothiazine-4-carbaldehyde was dissolved in 100 ml of tetrahydrofuran and reduced with 22 ml of lithium borohydride solution (1M in tetrahydrofuran) analogously to that described in Example 4.1.8.b. The crude product was chromatographed on silica gel with ethyl acetate/hexane (1:1), whereupon, after drying in a high vacuum, 6.44 g (70.3%) of [3,7-dimethoxy-6-(2-methoxy-ethoxymethoxymethyl)-10-methyl-phenothiazin-4-yl]-methanol were obtained as light yellowish oil.
