2-Bromopropanedial → 6-bromo-1H,3H-2,4,7a,8-tetraaza-cyclopenta[a]indene-2-carboxylic acid tert-butyl ester

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Reaction Steps

A mixture of bromomalonaldehyde (2.02 g; 13.38 mmol; 1 eq.) and 3-amino-2,6-dihydro-4H-pyrrolo[3,4-c]pyrazole-5-carboxylic acid tert-butyl ester (3 g; 13.38 mmol; 1 eq.) in AcOH (21 mL) was stirred at room temperature for 40 minutes. The insoluble material was removed by filtration and the solution diluted with water (60 mL). The precipitate was filtered off, washed with water (3×) and dried. Recrystallization from iPrOH afforded the title compound (2.02 g, 45%) as beige solid. 1H NMR (DMSO-d6) δ 9.60 (d, J=2.2 Hz, 1H), 8.60 (d, J=2.2 Hz, 1H), 4.62-4.55 (m, 4H), 1.47 (s, 9H). HPLC (max plot) 99.8%; Rt 3.54 min. UPLC/MS: (MS+) 339.3 and 341.3 ([M+H]+).

Provenance & Evidence