3,4-dihydro-2H-pyran → N-[[4-[2-(5-hydroxypentylidene)hydrazinyl]phenyl]methyl]methanesulfonamide

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Reaction Steps

To a solution of 23.9 g of crude N-[(4-hydrazinylphenyl)methyl]methanesulfonamide hydrochloride in 175 mL of water and 300 mL of ethanol was added sufficient sodium acetate to bring the pH to 4. To the resulting suspension was added 10.4 mL (114 mmol, 1.3 equiv.) of 3,4- dihydro-2H-pyran. The mixture was then stirred for twenty hours at room temperature. The ethanol was removed in vacuo. The pH was raised to 10 by adding solid potassium carbonate and the mixture was extracted three times with 50 mL portions of methylene chloride. The combined organic layers were washed with 25 mL of saturated aqueous sodium chloride, dried over magnesium sulfate and filtered to give an oil. The oil was purified by chromatography on silica gel using 5% methanol in methylene chloride containing 0.5% concentrated aqueous ammonium hydroxide to yield 11.1 g (39%, two steps) of pure N-[[4-[2-(5-hydroxypentylidene)hydrazinyl]phenyl]methyl]methanesulfonamide.

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