Synthesis and antitumor activity of novel α‐aminophosphonates from diterpenic dehydroabietylamine

A series of novel α‐aminophosphonates were synthesized from diterpenic dehydroabietylamine, and their structures were characterized by IR, 1 H NMR, and 31 P NMR spectroscopy. Their antitumor activities against SMMC7721 liver cancer cells were evaluated by the MTT method. Compounds 4 and 6 exhibited higher activities even at very low concentrations, and the inhibition ratios reached 75% and 79% at 0.1 µM, respectively. The inhibition ratio of compound 9 reached 99% after 72‐h incubation. α‐Aminophosphonates with a fluorine atom and a nitro group fused to the benzene ring exhibited higher activities.