Methanethiol → Guanidine Sulfate (1:1)

Temperature

50 °C

To a solution of 7-(1-aminobutyl)camptothecin (2.10 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 2.60 g (93%) of guanidine sulfate. Colorless solid, MP 292-293° C.(dec.). IR (KBr): 2400-2620, 1775, 1650 cm−1. 1H NMR (D2O) δ 7.58 (1H, d, J 8.7 Hz), 7.46-7.35 (3H, m), 7.17 (1H, m), 5.17 (1H, d, J 16.5 Hz), 4.55 (1H, d), 2.98 (2H, m), 2.92-2.80 (4H, m), 1.82-1.47 (6H, m), 0.83 (1H, t, J 7.3 Hz). C25H29 N5O8S (559.6). Ms m/z: 559 (M+). Anal. Calcd for C25H29 N5O8S (559.6): C, 53.66: H, 5.22: N, 12.51. Found: C, 53.56; H, 5.41; N, 12.34.

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-10380572842c4806956cfc4327a74423

Source dataset

uspto-grants-2001_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US06291676B1