[Br:1]Br.C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.O[CH2:23][CH2:24][C:25]1[S:29][C:28]([C:30]([O:32][CH:33]([CH3:35])[CH3:34])=[O:31])=[CH:27][CH:26]=1.N1C=CC=CC=1>C(Cl)Cl>[Br:1][CH2:23][CH2:24][C:25]1[S:29][C:28]([C:30]([O:32][CH:33]([CH3:35])[CH3:34])=[O:31])=[CH:27][CH:26]=1
Bromine (1.74 mL, 33.9 mmol) was added slowly to a solution of triphenylphosphine (8.9 g, 33.9 mmol) in CH2Cl2 (65 mL) at −40° C. After 1 h at −40° C., a solution of the alcohol from step 1 (6.6 g, 30.8 mmol) and pyridine (2.5 mL, 30.9 mmol) in CH2Cl2 (65 mL) was added via cannula. The mixture was allowed to warm to room temperature and was stirred overnight. The reaction was concentrated in vacuo to a brown slurry. The mixture was triturated with hexanes (150 mL) and stirred vigorously. The solids were removed by filtration and the filtrate was concentrated in vacuo to afford 6.2 g (73%) of isopropyl 5-(2-bromoethyl)thiophene-2-carboxylate.
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