Dicyclohexylcarbodiimide → Urea

Participants

Reaction Steps

Conjugation Via Leu-Ala-Leu-Ala Spacer: The N-hydroxysuccinimide ester of aminopterin was prepared as above. To 10.2 ml of a 23 mM solution of the aminopterin derivative (0.236 mmol) in dimethylformamide were added 104 mg (0.236 mmol) of solid L-Leu-L-Ala-L-Leu-L-Ala (LALA). The mixture was stirred overnight at 50° C. during which time the solid LALA dissolved. To the reaction mixture was added 48.7 mg (0.236 mmol) of dicyclohexylcarbodiimide in 0.58 ml of dimethylformamide. Copious quantities of urea formed within 2 hours at room temperature and were removed by filtration. The filtrate containing the N-hydroxy succinimide ester of the LALA derivative of aminopterin was retained.

Provenance & Evidence