Formation of squaric acid amides of anthracycline antibiotics. Synthesis and cytotoxic properties.

@article{Tevyashova2004FormationOS,
  title={Formation of squaric acid amides of anthracycline antibiotics. Synthesis and cytotoxic properties.},
  author={Anna N Tevyashova and Ferenc Sztaricskai and Gyula Batta and P{\'a}l Herczegh and Andr{\'a}s Jeney},
  journal={Bioorganic & medicinal chemistry letters},
  year={2004},
  volume={14 18},
  pages={4783-9}
}
The reaction of the anthracycline glycoside antibiotics 1-3 with the squaric acid ester 4 gave the squaric acid amide esters 5-7 under neutral conditions, whereas over pH7 the products are the symmetric diamides (8, 9, 11, and 12). Of the prepared compounds 11 was the most active on MCF-7 human mammary adenocarcinoma cells.