Methyl morpholine oxide → 5-[(2-Methoxyethyl)(methyl)amino]-3-methyl-1-benzofuran-2-carbaldehyde

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Reaction Steps

A solution (10 mL) of methyl 5-[(2-methoxyethyl)(methyl)amino]-3-methyl-1-benzofuran-2-carboxylate (2.7 g) synthesized in the above-mentioned (1) in tetrahydrofuran was added to an ice-cooled solution (40 mL) of lithium aluminum hydride (0.38 g) in tetrahydrofuran. The ice bath was removed, and the reaction mixture was stirred at room temperature for 1 hr then ice-cooled again, and water (1.0 mL), 1N aqueous sodium hydroxide solution (5.0 mL) and water (1.0 mL) were successively added dropwise to quench the reaction. The residue was filtered through celite, and the filtrate was concentrated under reduced pressure to give a crude product (0.41 g) of {5-[(2-methoxyethyl)(methyl)amino]-3-methyl-1-benzofuran-2-yl}methanol as a pale-yellow oil. The obtained oil was dissolved in acetonitrile (20 mL), tetrapropylammonium perruthenate (0.07 g) and N-methylmorpholine N-oxide (0.46 g) were added to the solution at room temperature, and the mixture was stirred for 30 min. The solvent was evaporated under reduced pressure, and the residue was purified by silica gel column chromatography (ethyl acetate:hexane=1:2, volume ratio) to give the title object compound (0.09 g, 3%) as a yellow oil.

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