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: purchase@heterocycles.com

Price: ¥ 4,320 (Yen only)
Period: This Article can be accessed for 7 days.

Paper | Regular issue | Vol 87, No. 7, 2013, pp.1507-1517
Published online, 15th May, 2013
DOI: 10.3987/COM-13-12728
A Convenient Two-Step Synthesis of 7-Aryl-6,7-dihydrothieno[2,3-b]pyrazines from Aryl(3-chloropyrazin-2-yl)methanones

Kazuhiro Kobayashi,* Teruhiko Suzuki, and Naoki Matsumoto

*Division of Applied Chemistry, Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, 4-101 Koyama-minami, Tottori 680-8552, Japan

Abstract

An efficient method for the preparation of 7-aryl-6,7-dihydrothieno[2,3-b]pyrazines (3) under mild conditions has been developed. The reaction of aryl(3-chloropyrazin-2-yl)methanones (1), derived from commercially available 2-chloropyrazine, with methylenetriphenylphosphorane in THF at room temperature gave the corresponding 2-(1-arylethenyl)-3-chloropyrazines (2), which were treated with NaSH·nH2O in DMF at room temperature to lead to the desired products (3) in acceptable yields. These products are dehydrogenated with air in refluxing toluene in the presence of a catalytic amount of Pd/C to yield the corresponding 7-arylthieno[2,3-b]pyrazines (4).