Microwave-Assisted Synthesis of Acyclic C-Nucleosides from 1,2- and 1,3-Diketones

Abstract

A simple, rapid and regioselective approach for the synthesis of C-acyclic nucleosides 3, 4, 6, and 9 of dihydropyrimidine, imidazole and indeno[1,2-b]pyridine-9-one derived from 1,2- and 1,3-diketones was performed. By using DMF or pyridine as solvent or bentonite clay as a support, in the presence of TMSTf, ZnCl₂, NH₄OAc, or NH₄NO₃, all the desired products were obtained within 5–25 minutes under microwave irradiation (MWI). Acid hydrolysis of 6 and 9 afforded the free acyclic C-nucleosides 7 and 10, respectively. Upon treatment with NaOMe under MWI, 3 and 14 rearranged to the C-nucleoside 4 and 16.

Keywords:

• Acyclic C-nucleosides
• Beginelli reaction
• ß-diketones
• microwave-assisted synthesis
• pyrimidinones