Dichloromethane → 6-[2-(5-Chloro-2,4-dimethoxy-phenyl)ethyl]-6-cyclopentyl-tetrahydropyran-2,4-dione

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Reaction Conditions

Reaction Steps

A solution of 6-[2-(2,4-dimethoxyphenyl)ethyl]-6-cyclopentyldihydro-2H-pyran-2,4(3H)-dione (from Step 5, above) (4.50 g, 13 mmol) in CH2Cl2 (20 mL) was cooled to −5° C. and treated with a solution of SO2Cl2 (1.94 g, 14.3 mmol) in CH2Cl2 (10 mL) dropwise under nitrogen. The reaction mixture was stirred for an additional 15 minutes at −5° C., then allowed to warm gradually to room temperature. After a total reaction time of 2 h, an aqueous solution of NaHCO3 (5 wt %) was added to achieve a pH of 8 in the aqueous phase. The volatiles were removed in vacuo. The residue was treated with water and extracted with ethyl acetate (3×25 mL). The combined ethyl acetate extract was acidified to a pH 2 using 2 N HCl, then washed with water. The organic phase was dried over Na2SO4, filtered, and concentrated to a yellowish solid. Recrystallization from ether afforded the title product as a white solid (2.18 g, 44%). 1H NMR (CDCl3) δ1.74 (m, 8H), 2.32 (m, 1H), 2.58 (m, 2H), 2.78 (s, 2H), 3.43 (s, 2H), 3.82 (s, 3H), 3.92 (s, 3H), 6.44 (s, 1H), 7.07 (s, 1H). HRMS calcd for C20H25O5Cl (M+H+): 381.1469, found 381.1475.

Provenance & Evidence