2,2,6,6-Tetramethylpiperidine → (2,3,4-Trimethoxy-6-methylphenyl)(5-bromo-4-chloro-2-methoxy-3-pyridyl)methanol

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

18.3 ml of n-butyllithium (1.57 mol/l hexane solution, 27 mmol) was dropwise added at 0° C. to a solution having 3.84 g (27 mmol) of 2,2,6,6-tetramethylpiperidine dissolved in 36 ml of tetrahydrofuran under an argon stream, followed by stirring at 0° C. for 30 minutes. The obtained solution was cooled to −78° C., and a solution having 6.10 g (27 mmol) of 5-bromo-4-chloro-2-methoxypyridine dissolved in 24 ml of tetrahydrofuran was added, followed by stirring at the same temperature for 2 hours to prepare 5-bromo-4-chloro-2-methoxy-3-pyridyllithium. Then, a solution having 5.50 g (26 mmol) of 2,3,4-trimethoxy-6-methylbenzaldehyde dissolved in 24 ml of tetrahydrofuran was added, followed by stirring at the same temperature for 1 hour. To the reaction mixture, 37 ml of a saturated ammonium chloride aqueous solution and then 150 ml of water were added, and the temperature was increased to room temperature, followed by extraction with ethyl acetate (150 ml each) three times. The organic layer was washed with a saturated sodium chloride solution (100 ml), dried over magnesium sulfate and subjected to filtration, and the solvent was distilled off under reduced pressure. The obtained crude product was purified by silica gel chromatography to obtain 6.53 g (yield: 56%) of (2,3,4-trimethoxy-6-methylphenyl)(5-bromo-4-chloro-2-methoxy-3-pyridyl)methanol.

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