open access

https://hdl.handle.net/2115/87974

Strain-Induced Ring Expansion Reactions of Calix[3]pyrrole-Related Macrocycles

英語

strained molecules

2022-03-22

Wiley-Blackwell

Chemistry-A European journal

28(17)

e202200056

The recent discovery of calix[3]pyrrole, a porphyrinogen-like tripyrrolic macrocycle, has provided an unprecedented strain-induced ring expansion reaction into calix[6]pyrrole. Here, we synthesized calix[n]furan[3-n]pyrrole (n=1 similar to 3) macrocycles to investigate the reaction scope and mechanism of the ring expansion. Single crystal X-ray analysis and theoretical calculations revealed that macrocyclic ring strain increases as the number of inner NH sites increases. While calix[1]furan[2]pyrrole exhibited almost quantitative conversion into calix[2]furan[4]pyrrole within 5 minutes, less-strained calix[2]furan[1]pyrrole and calix[3]furan were inert. However, N-methylation of calix[2]furan[1]pyrrole induced a ring-expansion reaction that enabled the isolation of a linear reaction intermediate. The mechanism analysis revealed that the ring expansion consists of regioselective ring cleavage and subsequent cyclodimerization. This reaction was further utilized for synthesis of calix[6]-type macrocycles.

学術雑誌論文

Accepted Manuscript

This is the peer reviewed version of the following article: Y. Inaba, Y. Kakibayashi, Y. Ide, J. Pirillo, Y. Hijikata, T. Yoneda, Y. Inokuma, Chem. Eur. J. 2022, 28, e202200056, which has been published in final form at https://doi.org/10.1002/chem.202200056. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.

0947-6539