C[Si]([N-][Si](C)(C)C)(C)C.[K+].C1OCCOCCOCCOCCOCCOC1.[C:29]([O:33][C:34](=[O:52])[CH2:35]P(OC1C=CC=CC=1)(OC1C=CC=CC=1)=O)([CH3:32])([CH3:31])[CH3:30].[S:53]1[C:57]([CH:58]=O)=[CH:56][C:55]2[CH:60]=[CH:61][CH:62]=[CH:63][C:54]1=2>C1COCC1>[C:29]([O:33][C:34](=[O:52])[CH:35]=[CH:58][C:57]1[S:53][C:54]2[CH:63]=[CH:62][CH:61]=[CH:60][C:55]=2[CH:56]=1)([CH3:32])([CH3:31])[CH3:30]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.
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