Sulfuric Acid → 9-methoxy-4-propyl-1,2,3,4a,5,10b-hexahydro-4H-[1]-benzopyrano[3,4-b]pyridine

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Reaction Steps

To a suspension of 3.8 g of lithium aluminium hydride in 100 ml of tetrahydrofuran, 3.6 g of concentrated sulfuric acid is added dropwise at -5° to -10°, then 5.0 g of 9-methoxy-4-propionyl-1,2,3,4a,5,10b-hexahydro-4H-[1]-benzopyrano[3,4-b]pyridine is added slowly with stirring. The reaction mixture is allowed to warm to room temperature, stirred for 18 hours and finally heated under reflux for 1 hour. After cooling the reaction mixture is quenched with ethyl acetate, then treated with a small volume of water and 3N sodium hydroxide, filtered and concentrated in vacuo. The residue is redissolved in ethyl acetate and the ethyl acetate solution is washed with water, dried and evaporated to yield 9-methoxy-4-propyl-1,2,3,4a,5,10b-hexahydro-4H-[1]-benzopyrano[3,4-b]pyridine. The starting material is prepared by treatment of 9-methoxy-1,2,3,4a,5,10b-hexahydro-4H-[1]-benzopyrano[3,4-b]pyridine in the presence of two mole equivalents of powdered potassium carbonate in methylene chloride solution with 1 mole of propionyl chloride at room temperature overnight.

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