18-Crown-6 → 3-Benzo[b]thiophen-2-yl-acrylic acid tert-butyl ester

Participants

Reaction Steps

Potassium bis(trimethylsilyl)amide (5.4 g, 0.027 mol) was added to a solution of 18-Crown-6 (13.7 g, 0.052 mol) and (diphenoxy-phosphoryl)-acetic acid tert-butyl ester (9.4 g, 0.027 mol) in dry THF (120 mL) at −780C. After 30 minutes of stirring at this temperature, benzo[b]thiophene-2-carbaldehyde (4.0 g, 0.024 mol) was added and the reaction was stirred for 3 hours at −780C after which the reaction was quenched with saturated ammonium chloride (200 mL). The reaction mix was allowed to come to room temperature and was extracted with ethyl acetate (3×200 mL) and the combined organic extracts were washed with 10% HCl (200 mL), brine (200 mL), and dried over MgSO4. The solvent was evaporated in vacuo leaving the crude product that was purified by column chromatography (SiO2) using a 5-40% ethylacetate-hexane gradient to afford the subtitle compound (4.64 g, yield: 74%). MS calculated for C15H16O2S+H: 261, observed: 261.

Provenance & Evidence