1-Piperidinecarboxaldehyde → [6-(Tert.-butyl-dimethyl-silanyloxymethyl)-3,7-dimethoxy-10-methyl-phenothiazine4-yl]methanol

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Reaction Steps

A solution of 4.56 g (10.9 mmol) of 4-(tert.-butyl-dimethyl-silanyloxymethyl)-3,7-dimethoxy-10-methyl-phenothiazine in 50 ml of diethyl ether/tetrahydrofuran (4:1) was reacted with 7.5 ml of n-butyllithium solution (1.6M in hexane) and 1.89 g (16.84 mmol) of N-formylpiperidine analogously to that described in Example 4.1.1c. The resulting 3,7-dimethoxy-4-(tert.butyldimethylsilanyloxymethyl)-10-methylphenothiazine-carbaldehyde was dissolved in 50 ml of tetrahydrofuran and reduced with 12.0 ml of lithium borohydride solution (1M in tetrahydrofuran) analogously to that described in Example 4.1.8.b. The reaction mixture was poured into ice/1M sodium dihydrogen phosphate solution, whereupon the mixture was extracted three times with ethyl acetate. The combined organic phases were washed with saturated sodium chloride solution, dried over magnesium sulphate and concentrated. The residue was chromatographed on silica gel with ethyl acetate/hexane (1:1), whereupon, after recrystallization from ethyl acetate/hexane and drying, 3.30 g (67.6%) of [6-(tert.-butyl-dimethyl-silanyloxymethyl)-3,7-dimethoxy-10-methyl-phenothiazine4-yl]methanol were obtained as a white solid of m.p. 46°-47°.

Provenance & Evidence