- Replacing the cyclohexene-linker of FR181157 leading to novel IP receptor agonists: orally active prostacyclin mimetics. Part 6. Tanaka, A., Hattori, K., Taniguchi, K., Okitsu, O., Tabuchi, S., Nishio, M., Nagakura, Y., Maeda, N., Murai, H., Seki, J. Bioorg. Med. Chem. Lett. (2006)