Patent ID: 7928235

Claim:
A method of making an aliphatic ester of camptothecin comprising reacting a starting camptothecin compound with at least one acylating agent and at least one acid that is concentrated acid, wherein said at least one acid is present in a catalytic amount and said at least one acylating agent is protonated by said at least one acid and said starting camptothecin compound is 20(S)-camptothecin, 9-nitro-camptothecin, or 9-aminocamptothecin, and said acylating agent has the formula (R 1 CO) 2 O, wherein R 1 represents CH 3 ; C 2 H 5 ; C 3 H 7 ; C 4 H 9 ; C 6 H 13 ; C 8 H 17 ; or CH═CHCH 3 ; and wherein at least 90% by weight of said starting camptothecin compound is converted to said aliphatic ester of camptothecin.