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Paper | Special issue | Vol 101, No. 1, 2020, pp.273-283
Published online, 1st August, 2019
DOI: 10.3987/COM-19-S(F)23
Conformational Properties and M1 Antimuscarinic Activity of 4-Substituted Pirenzepine/Telenzepine Analogues

Yuki Kanase, Kosho Makino, Takashi Yoshinaga, Hidetsugu Tabata, Tetsuta Oshitari, Hideaki Natsugari, and Hideyo Takahashi*

*Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-8510, Japan


The atropisomeric and conformational properties of the 4-Cl/Me-substituted pirenzepine/telenzepine analogues were examined. Although the 4-substitution is not effective in reducing the rotational barrier of the N5–(C1'=O) bond, the butterfly motion of the tricyclic ring system was frozen. The atropisomers showed little racemization after heating at 80 °C for 5 days. While these analogues showed less affinity to the M1 receptor compared with pirenzepine, a ca. 4.4-fold difference in potency between the atropisomers was observed for 1b.