N-bromobutanimide → tert-butyl 5-bromo-6-cyclohexyl-4-(2-methoxy-2-oxoethyl)-4H-thieno[3,2-b]pyrrole-2-carboxylate

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Reaction Conditions

Reaction Steps

tert-Butyl 6-cyclohexyl-4-(2-methoxy-2-oxoethyl)-4H-thieno[3,2-b]pyrrole-2-carboxylate (1 eq., from Step 2) was dissolved in anhydrous CH2Cl2, cooled to 0° C. and treated portionwise over 40 mins with N-bromosuccinimide (1 eq.). The reaction mixture was quenched by the addition of 1 M sodium thiosulfate solution and extracted with EtOAc. The combined organic layers were washed with 1 M sodium thiosulfate solution and with brine and dried over sodium sulfate. Evaporation afforded the pure title compound (87%) as light-yellow foam. 1H-NMR (400 MHz, DMSO-d6, 300 K, δ) 7.86 (s, 1H), 5.12 (s, 2H), 3.69 (s, 3H), 2.67-2.56 (m, 1H), 1.81-1.70 (m, 5H), 1.52 (s, 9H), 1.52-1.27 (m, 5H). MS (ES+) m/z: 456, 458 [M+H]+.

Provenance & Evidence