A series of 5-C-alkylating camptothecins have been synthesized by one-step method,and their ill vitro antitumor activity was evaluated against six human cancer cell lines.The results showed that all 5-C-alkylates of camptothecins possessed poor cytotoxicity on six human cancer cell lines. A series of 5-C-alkylating camptothecins have been synthesized by one-step method, and their ill vitro antitumor activity was evaluated against six human cancer cell lines. The results showed that all 5-C-alkylates of camptothecins possessed poor cytotoxicity on six human cancer cell lines.