Online article for Non-subscribers

Pay per view

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:

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

Communication | Special issue | Vol 64, No. 1, 2004, pp.57-60
Published online, 2nd November, 2004
DOI: 10.3987/COM-04-S(P)36
Mode Switching during the Cycloaddition of 5-Fluoro-1,3-dimethyluracil with Naphthalene from 1,4- to 1,2-Addition

Kazue Ohkura,* Tatsuyuki Sugaoi, Tetsuya Ishikara, and Koh-ichi Seki*

*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan


UV-irradiation of a solution of 5-fluoro-1,3-dimethyluracil (5-FDMU) and naphthalene (1) in acetonitrile effected both 1,2- and 1,4-cycloaddition. The 1,2-cycloaddition proceeds more smoothly than the alternative 1,4-cycloaddition. The 1,2-cycloadduct (2), however, is labile to the UV-light used for the reaction, and is rapidly converted to 5-FDMU and naphthalene, while the 1,4-adduct (3) is insensitive to UV-light. Thus, 2 is obtained as the major product by short-period irradiation, while 3 is produced predominantly when the irradiation duration is prolonged. Mode-selective 1,2-cycloaddition is achieved when UV-irradiation is performed in the presence of piperylene.