Thionyl Chloride → 6-methoxy-3,4-dihydro-2H-1-benzopyran-4-one

関与物質

反応手順

Cyclisation is carried out on the acid chloride generated starting from the acid. Heating the acid obtained in Step B (500 mg:2.55 mmol) at reflux of toluene (20 ml) for 3 hours in the presence of thionyl chloride (0.56 ml:7.65 mmol:3 eq.) allows easy access to the acid chloride. The solvent and also the excess reagent are removed by concentrating the resulting yellow solution under reduced pressure. The dry residue is then taken up in 20 ml of anhydrous dichloromethane; aluminium chloride (465.9 mg:3.49 mmol:1.5 eq.) is then introduced cautiously. The reaction mixture is hydrolysed in the cold state after 1 hour of stirring at ambient temperature. The product is extracted, washed with water and then purified on a silica column (AcOEt/PE 3/7).

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