3,4-Dichlorobenzaldehyde → 3-(3,4-Dichlorophenylmethylene)-1-(4-fluorobenzenesulfonyl)-5-methyl-2-pyrrolidinone

Participants

Reaction Conditions

Reaction Steps

A flame dried flask was charged with 332 mg 1-(4-fluorobenzenesulfonyl)-5-methyl-2-pyrrolidinone (prepared above, 1.29 mmol, 1.0 equiv) and 10 mL THF under N2. The solution was cooled to −78° C. followed by the addition of 1.68 mL of a 1.0 M solution of sodium bis(trimethylsilyl)amide (1.68 mmol, 1.3 equiv). The solution was allowed to stir for an additional 40 min followed by the addition of 271 mg 3,4-dichlorobenzaldehyde (1.54 mmol, 1.2 equiv) in 2 mL THF. After stirring an additional 10 min, the solution was diluted with 10 mL 0.1 N HCl and allowed to warm to rt. The solution was then extracted (3×Et2O), washed with brine, dried (MgSO4), and concentrated under reduced pressure. Purification via flash chromatography (SiO2, 1% MeOH/CH2Cl2) gave the product 3-(3,4-dichlorophenylmethylene)-1-(4-fluorobenzenesulfonyl)-5-methyl-2-pyrrolidinone as a white foam (39 mg, 0.0937 mmol, 7%). 1H NMR (DMSO, 400 MHz) δ 8.28 (m, 2 H), 7.96 (d, J=2 Hz, 1H), 7.85 (d, J=8.4 Hz, 1 H), 7.70-7.63 (m, 3 H), 7.45 (t, J=2.9 Hz, 1 H), 4.86 (m, 1 H), 3.59 (m, 1 H), 2.92 (m, 1 H), 1.56 (d, J=6.0 Hz, 3 H).

Provenance & Evidence