HETEROCYCLES

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact: purchase@heterocycles.com

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

■ Direct Observation of ESR Spectra of Bicyclic Nine-Membered Enediynes at Ambient Temperature

Masahiro Hirama,* Kimio Akiyama,* Parthasarathi Das, Takashi Mita, Martin J. Lear, Kyo-ichiro Iida, Itaru Sato, Fumihiko Yoshimura, Toyonobu Usuki, and Shozo Tero-Kubota

*Department of Chemistry, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan

Abstract

The ESR spectra for synthetic bicyclo[7.3.0]epoxydodecadienediynes in solution at room temperature are steady. These spectra originate from the Masamune-Bergman cyclization of bicyclo[7.3.0]epoxydodecadienediynes to p-benzyne biradicals and the equilibrium between the two forms. Comparison of the ESR spectra of the unlabeled and ¹³C-labeled nine-membered enediynes indicated that the spectra are not directly due to the p-benzyne biradicals but rather to more stable secondary radical intermediates.