Methanethiol → Guanidine Sulfate (1:1)

Temperature

50 °C

To a solution of 7-(1-aminopentyl)camptothecin (2.16 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 2.72 g (95%) of guanidine sulfate. Colorless solid, MP 289-291° C.(dec.). IR (KBr): 2400-2620, 1775, 1650 cm−1. 1H NMR (DMSO-d6) δ 8.24 (1H, d, J 7.0 Hz), 7.80 (1H, m), 7.73 (1H, m), 5.42 (2H, s), 5.26 (2H, s), 3,11 (2H, m), 2.96 (2H, m), 1.82 (2H, m), 1.66-1.51 (6H, m), 8.87 (3H, t, J 6.8 Hz). C26H31N5O8S (573.63). Ms m/z: 573 (M+). Anal. Calcd for C26H31 N5O8S (573.63): C, 54.44: H, 5.45: N, 12.21. Found: C, 54.68; H, 5.31; N, 12.38.

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-9dff85ad1adf4c39b74173a41d9069ed

Source dataset

uspto-grants-2001_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06291676B1