Butanal → Methyl 3-ethyl-6-(propan-2-yl)azulene-1-carboxylate

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Reaction Steps

n-Butyraldehyde (61.5 g, 0.853 mole) and morpholine (61.9 g, 0.71 mole) are added to cooled ethanol (400 ml), and then the compound (5) (68 g, 0.276 mole) is added thereto. The obtained mixture is stirred and warmed to dissolve the solid substance homogeneously. It is heated under reflux for 8 hours, and then the solvent is distilled off under reduced pressure to precipitate an oily material. The obtained oily material is dissolved in benzene (450 ml), washed twice with the same volume of water, three times with 1N HCl (400 ml), and further twice with water (400 ml). The obtained benzene solution is passed through alumina (500 g), and the eluted solution is concentrated to obtain the compound (1) at a yield of 57.4 g, 81.2%. It is recrystallized in n-hexane to give the purified product (55 g) in the purple crystalline form.

Provenance & Evidence