Dihydrocoumarin → Cyclohexadienone, hydroxy-

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Reaction Steps

The Grignard reagent of 4-chloro-N-methylpiperidine (60 g, 0.47 moles) is prepared as in Example 3A. To this is added a solution of 23 g (0.155 moles) dihydrocoumarin in 100 ml tetrahydrofuran over 20 minutes (reaction is refluxed). Refluxed for 31/2 hours. The flask is cooled in an ice bath and saturated ammonium chloride solution is added (200 ml). The layers are separated and the aqueous extracted with tetrahydrofuran. The organics are dried (magnesium sulfate) and evaporated. The residue, after an acid-base extraction, yield 13 g from the organics. Carbon dioxide is bubbled through the aqueous which is then extracted with dichloromethane. These organics are dried and evaporated to yield 26 g. Chromatography (basic alumina, activity III, chloroform) afforded 17.7 g (46%) crystalline keto-phenol.

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