A CONVENIENT TWO-STEP SYNTHESIS OF 7-ARYL-6,7-DIHYDROTHIENO[2,3-b]PYRAZINES FROM ARYL(3-CHLOROPYRAZIN-2-YL)METHANONES

作者：Kobayashi Kazuhiro^*; Suzuki Teruhiko; Matsumoto Naoki

来源：Heterocycles, 2013, 87(7): 1507-+.

DOI：10.3987/COM-13-12728

• 6,7-Dihydrothieno[2,3-b]pyrazine
• Thieno[2,3-b]pyrazine
• 2-Chloropyrazine
• Sodium Hydrogen Sulfide
• Dehydrogenation

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 center dot nH(2)O 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).

• 出版日期2013-7-1