B-Ring-Aryl Substituted Luotonin A Analogues with a New Binding Mode to the Topoisomerase 1-DNA Complex Show Enhanced Cytotoxic Activity
Figure 2
Preparation of synthetic precursors.
Compounds 1a–d are commercially available. Compound 1e was prepared by bromination of 1c, using a literature method. Compounds 1f and 1g were prepared by addition of 3,5-dimethylphenylmagnesium bromide to the corresponding 2-aminobenzonitrile derivative to generate an imine that was hydrolyzed in situ by addition of acid.