Synthetic studies connected with the preparation of N-[3-(3-cyanopyrazolo[1,5-a]pyrimidin-5-yl)phenyl]-N-ethylacetamide, a zaleplon regioisomer

Abstract

N-[3-(3-Cyanopyrazolo[1,5-a]pyrimidin-5-yl)phenyl]-N-ethylacetamide, a principal impurity of zaleplon, is prepared by Suzuki-Miyaura cross coupling reaction of the corresponding boronic acid and/or boronates with 5-chloropyrazolo[1,5-a]pyrimidin-3-carbonitrile (7). Various methods of preparation of both components are described, as well as approaches based on the final modification of the 5-(3-aminophenyl)-pyrazolo[1,5-a]pyrimidine-3-carbonitrile moiety prepared by Suzuki-Miyaura cross coupling.

All the prepared compounds were unambiguouesly identified by NMR techniques. Spectral characteristics (IR, UV, MS) of these compounds are also given.

Keywords

• zaleplon regioisomer
• synthesis
• spectral property
• 5-arylpyrazolo[1,5-a]pyrimidine-3-carbonitrile
• Suzuki-Miyaura cross coupling reaction