N-bromobutanimide → Ethyl 2-(2-bromothiophen-3-yl)acetate
Reaction equation
[S:1]1[CH:5]=[CH:4][C:3]([CH2:6][C:7]([O:9][CH2:10][CH3:11])=[O:8])=[CH:2]1.C1C(=O)N([Br:19])C(=O)C1>C1COCC1>[Br:19][C:2]1[S:1][CH:5]=[CH:4][C:3]=1[CH2:6][C:7]([O:9][CH2:10][CH3:11])=[O:8]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
To a solution of ethyl 2-(thiophen-3-yl)acetate (1, 20.30 g, 119.25 mmol) in THF (150 mL) was added NBS (21.23 g, 119.25 mmol) over a period of 5 hours at 0° C., and then the mixture was warmed up to room temperature, stirring continuously for 24 hours. The solvent was removed in vacuo, and the residue was dissolved in EtOAc (150 mL) and washed with brine (4×30 mL). The organic layer was dried over MgSO4, filtered, and then concentrated in vacuo. MPLC purification (Hex/EtOAc 5:1) of the residue gave ethyl 2-(2-bromothiophen-3-yl)acetate as a colorless oil (24.00 g, 81%). 1H NMR (400 MHz, CDCl3) δ 7.23 (d, J=5.4 Hz, 1H), 6.93 (d, J=5.4 Hz, 1H), 4.17 (q, J=7.2 Hz, 2H), 3.61 (s, 2H), and 1.27 (t, J=7.2 Hz, 3H); 13C NMR (100 MHz, CDCl3) δ 170.37, 133.84, 128.90, 125.93, 111.78, 61.32, 35.30, and 14.43.