Diisopropylethylamine → N'-(8-Bromo-4,5-dihydro-6-oxa-1,3a-diaza-benzo[e]azulene-2-carbonyl)-N'-isopropyl-hydrazinecarboxylic acid tert-butyl ester

Participants

Reaction Steps

To a mixture of 8-bromo-4,5-dihydro-6-oxa-1,3a-diaza-benzo[e]azulene-2-carboxylic acid (1.92 g, 6.2 mmol) and N′-isopropyl-hydrazinecarboxylic acid tert-butyl ester (1.30 g, 7.5 mmol) in DMF (20 mL) at 0° C. was added DIPEA (2.70 mL, 15.5 mmol) and HATU (3.54 g, 9.3 mmol). The reaction mixture was stirred for 7 h at RT before the addition of DMF (40 mL) and stirring overnight. The reaction mixture was concentrated in vacuo and the resultant residue partitioned between DCM and water. The aqueous phase was extracted with DCM (×2) before the combined organic extracts were washed sequentially with 10% citric acid solution, saturated sodium bicarbonate solution then brine, dried (Na2SO4) and concentrated in vacuo. The resultant residue was subjected to flash chromatography (SiO2, gradient 0-90% ethyl acetate in cyclohexane) to give N′-(8-Bromo-4,5-dihydro-6-oxa-1,3a-diaza-benzo[e]azulene-2-carbonyl)-N′-isopropyl-hydrazinecarboxylic acid tert-butyl ester as a white solid (3.02 g, quantitative yield). LCMS RT=4.76 min, [M+H]+=465/467. 1H NMR 400 MHz (DMSO-d6) δ: 8.62 (1 H, s), 8.40 (1 H, d, J=8.59 Hz), 7.69 (1 H, s), 7.23-7.22 (2 H, m), 4.81 (1 H, s), 4.44 (4 H, s), 1.32 (9 H, s), 1.13 (6 H, d, J=6.64 Hz)

Provenance & Evidence