Dimethyl Sulfate → HCID 91097000, compound

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Reaction Steps

The product of Step 1 (11.1 g) is dissolved in ethyl acetate (200 mL). DBU (4.05 g) and dimethyl sulphate (3.36 g) are added sequentially and the reaction mixture is stirred at room temperature for 2 hours, then partitioned between ethyl acetate and water. The organic layer is washed with water and brine, dried over magnesium sulphate and evaporated. Crystallisation from methanol affords 3-methylthiophene-2-carboxylic acid (6S,9S,10S,11S,13S,16R,17R)-9,11-epoxy-6-fluoro-17-methoxycarbonyl-10,13,16-trimethyl-3-oxo-6,7,8,9,10,11,12,13,14,15,16,17-dodecahydro-3H-cyclopenta[a]phenanthren-17-yl ester. Selected 1H-NMR signals (CDCl3) δ 0.90 (3H, d), 0.92 (3H, s), 1.40 (3H, s), 2.40 (3H, s), 3.65 (3H, s).

Provenance & Evidence