N-bromobutanimide → HCID 59648627, compound

Participants

Reaction Conditions

Reaction Steps

To a solution of ethyl 6H-thieno[2,3-b]pyrrole-5-carboxylate (0.55 g, 2.82 mmol) in DCM (10 mL) was added TBAF (1.0 M THF, 4.2 mL) followed by NBS (0.55 g, 3.1 mmol). The resulting mixture was allowed to stir at 23° C. for 1 h in the dark at which time the entire reaction mixture was placed on a silica gel column. Flash column chromatography (0-100% EtOAc in hexanes) affords one major peak containing a mixture of starting material, ethyl 4-bromo-6H-thieno[2,3-b]pyrrole-5-carboxylate, and 2,4-dibromo products. Separation of the desired products from the byproduct by RP-HPLC (10-100% gradient 0.1% formic acid in H2O to CH3CN over 10 min) afforded ethyl 4-bromo-6H-thieno[2,3-b]pyrrole-5-carboxylate (0.30 g, 39% yield) and ethyl 2,4-dibromo-6H-thieno[2,3-b]pyrrole-5-carboxylate (183 mg, 18%). Ethyl 2,4-dibromo-6H-thieno[2,3-b]pyrrole-5-carboxylate: 1H NMR (400 MHz, CD3OD) δ (ppm) 6.95 (s, 1H), 4.32 (q, J=4.6 Hz, 2H), 1.36 (t, J=7.0 Hz, 3H). LCMS m/e=351 (M+H).

Provenance & Evidence