Acetic Anhydride → trans-2-[3-(2-Oxopropylsulfonyl)-4-n-propoxy-5-benzyloxyphenyl]-5-(3,4,5-trimethoxyphenyl)tetrahydrofuran

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Reaction Steps

2.7 g trans-2-(3-methylsulfonyl-4-n-propoxy-5-benzyloxyphenyl)-5-(3,4,5-trimethoxyphenyl) tetrahydrofuran (STEP I) dissolved in 15 mL THF was cooled to -78° and treated with 5.3 mL of 1.6M n-BuLi. After about 5 minutes of stirring, to the resulting dark solution, 1.0 mL of acetic anhydride was added. The yellow reaction mixture was allowed to warm up to room temperature and treated with 3-4 g of solid ammonium chloride, water and ether. NMR showed that the desired ketosulfone has formed to the extent of 80%. The ether layer was separated, dried over NaSO4, evaporated and chromatographed over silica (20% ethyl acetate in hexane) to yield the title compound after crystallization from ether: NMR (200 MHz, CDCl3) δ 0.98 (t, CH2CH2CH3), 1.83 (m, CH2CH2CH3), 1.9-2.6 (m, 3-CH2 δ4-CH2), 2.38 (s, CH3C(O)CH 2), 3.86 (s, OCH3), 3.88 (s, 2 OCH3), 4.18 (t, OCH2CH2CH3), 4.48 (s, CH3C(O)CH2), 5.18 (s, OCH2Ar), 5.06-5.28 (m, 2-CH δ 5-CH), 6.61 (s, 5-ArH), 7.32-7.54 (m, ArH).

Provenance & Evidence