Water → Chroman

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Reaction Steps

A solution composed of 2 g (6.02 mmol) of the 3,4-dihydro-6-methoxy-2-[2-(piperazin-1-yl)ethyl]-2,5,7,8-tetramethyl-2H-benzopyran obtained by the process of Example 12 and 50 ml of tetrahydrofuran was cooled to -40° C. in a nitrogen atmosphere and, to this solution, 4.7 ml of a 15% solution of n-butyllithium in hexane was added gradually. The resultant mixture was stirred at -40° C. for 30 minutes. Then, 6.65 millimoles of the halogenated terpene compound (X') was added gradually thereto, and the resultant mixture was stirred at -40° C. for 30 minutes. After raising the temperature gradually to room temperature, the reaction mixture was poured into water and extracted with diethyl ether. The ether layer was dried over anhydrous sodium sulfate, and low-boiling substances were distilled off under reduced pressure. The residue was purified by silica gel column chromatography to give the corresponding 3,4-dihydrobenzopyran derivative. The yield and physical characteristics for each derivative thus obtained are shown in Table 19.

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