Triphenylphosphine → 6-(1-Isopropyl-piperidin-4-yloxy)-benzo[b]thiophene-2-carboxylic acid ethyl ester

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Reaction Steps

To 6-hydroxy-benzo[b]thiophene-2-carboxylic acid ethyl ester (0.300 g, 1.35 mmol, prepared as described above, but using ethyl instead of methyl thioglycolate), dissolved in 13.5 mL of THF, was added successively at 10° C. 1-isopropyl-piperidin-4-ol (0.387 g, 2 eq.), triphenylphosphine (0.708 g, 2 eq.) and DIAD (0.530 mL, 2 eq.), and the mixture then kept at this temperature for another 2 h. Pouring onto crashed ice, twofold extraction with AcOEt, washing with water and brine, drying over magnesium sulfate, and evaporation of all solvents, followed by flash chromatography (SiO2, MeOH/AcOEt=1/9), delivered 0.360 g of the title compound as off-white solid.

Provenance & Evidence