反应详情

The ethyl ester of step 1 (50.04 g, 250 mmol) and hydrazine hydrate (25.03 g, 50 mmol) were heated at 80° C. for 18 h. The excess hydrazine was removed under vacuum and the crude product was filtered through a pad of silica gel with EtOAc-Hexane (ca. 3 L) to furnish the title compound. 1H NMR (400 MHz, acetone-d6): δ 9.7 (s, 1H), 6.10 (s, 1H), 2.25 (m, 1H), 1.85 (m, 1H) and 0.95 t, (3H).

1. customThe excess hydrazine was removed under vacuum
2. filtrationthe crude product was filtered through a pad of silica gel with EtOAc-Hexane (ca. 3 L)