4-Toluenesulfonyl chloride → 4-Bromo-2-formyl-n-p-tosylpyrrole

Reaction equation

[H-].[Na+].[Br:3][C:4]1[CH:5]=[C:6]([CH:9]=[O:10])[NH:7][CH:8]=1.[C:11]1([CH3:21])[CH:16]=[CH:15][C:14]([S:17](Cl)(=[O:19])=[O:18])=[CH:13][CH:12]=1>C1COCC1>[CH3:21][C:11]1[CH:16]=[CH:15][C:14]([S:17]([N:7]2[C:6]([CH:9]=[O:10])=[CH:5][C:4]([Br:3])=[CH:8]2)(=[O:19])=[O:18])=[CH:13][CH:12]=1

Participants

Procedure

Following a reported procedure,18 a stirred suspension of NaH (865 mg, 36.0 mmol) in THF (200 mL) was treated with 6 (5.22 g, 30.0 mmol) at room temperature. When the evolution of gas had ceased, the mixture was stirred for 1 h before treating with p-toluenesulfonyl chloride (6.30 g, 33.0 mmol). After 16 h, the conversion was complete as monitored by TLC. The reaction mixture was quenched by adding aqueous NH4Cl. Ethyl acetate was added and the organic layer was separated. The organic layer was washed with water, brine and dried (Na2SO4). Concentration followed by crystallization (ethyl acetate/hexanes) afforded pale yellow crystals (6.75 g, 68%): mp 83-85° C.; 1H NMR δ 2.43 (s, 3H), 7.09 (d, J=2.0 Hz, 1H), 7.35 (d, J=8.3 Hz, 2H), 7.57 (d, J=2.0 Hz, 1H), 7.81 (d, J=8.3 Hz, 2H), 9.94 (s, 1H); 13C NMR δ 22.0, 101.8, 125.4, 127.8, 127.9, 130.6, 133.5, 134.7, 146.7, 178.5. Anal. Calcd or C12H10BrNO3S: C, 43.92; H, 3.07; N, 4.27; S, 9.77. Found: C, 43.92; H, 3.02; N, 4.26; S, 9.84.