Methanethiol → Guanidine Sulfate (1:1)

Temperature

50 °C

To a solution of 7-(1-aminopropyl)camptothecin (2.0 g, 5 mmol) in 10 ml of water was added S-methylisothiourea hemisulfate (0.7 g, 2.5 mmol) at room temperature. The mixture was heated at 50° C. for 5 hr under nitrogen. The gases developed during the reaction were passed through two flasks, each containing an ethanolic solution of KOH for trapping the CH3SH by-product. The mixture was then concentrated and 50 ml of acetone was added. The precipitate was filtered and recrystallized from water to give 2.59 g (95%) of guanidine sulfate. Colorless solid, MP 265-267° C.(dec.). IR (KBr): 2400-2600, 1770, 1650 cm−1. 1H NMR (D2O) δ 7.55 (1H, m), 7.47 (1H, s), 7.39 (1H, m), 7.27 (1H, m), 5.32 (1H, d, J 16.1 Hz), 5.19 (1H, d), 3.04 (2H, t, J 7.5 Hz), 2.92 (2H, d), 1.84 (4H, m), 0.86 (3H, t, J 7.1 Hz). C24H27N5O8S (545.57). Ms m/z: 545 (M+). Anal. Calcd for C24H27 N5O8S (545.57): C, 52.84: H, 4.99: N, 12.84. Found: C, 52.88; H, 4.63; N, 13.12.

1. concentrationThe mixture was then concentrated
2. addition50 ml of acetone was added
3. filtrationThe precipitate was filtered
4. customrecrystallized from water

ORD record

ord-97615a55cc584b2ea2bc17e871d5a827

Source dataset

uspto-grants-2001_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06291676B1