title: Impurity profile study of zaleplon.
abstract: Zaleplon is a pyrazolopyrimidine derivative and possesses sedative and hypnotic properties. Seven unknown impurities in zaleplon bulk drug at levels below 0.1% were detected by reverse-phase high performance liquid chromatography (HPLC). The starting material, 3-amino-4-cyanopyrazole and an intermediate, N-[3-[3-(dimethylamino)-1-oxo-2-propenyl]-phenyl]-N-ethylacetamide (DOPEA) were also present in the sample at a level below 0.1%. The molecular weights of impurities were determined by LC-MS analysis. These impurities were isolated from crude samples of zaleplon using reverse-phase preparative HPLC. Based on the spectral data the structures of these impurities were characterized as, N-(3-(3-(4-amino-2H-pyrazolo [3,4-d]pyrimidin-6-yl) pyrazolo[1,5-a] pyrimidin-7-yl)phenyl)-N-ethylacetamide (impurity I); N-[3-(3-carboxamidopyrazolo[1,5-a]pyrimidin-7-yl)phenyl]-N-ethylacetamide (impurity II); N-[3-(3-cyanopyrazolo[1,5-a]pyrimidin-7-yl)phenyl]acetamide (impurity III); N-[3-(3-cyanopyrazolo [1,5-a]pyrimidin-7-yl)phenyl]-N-methylacetamide (impurity IV); N-[3-(3-cyanopyrazolo[1,5-a] pyrimidin-5-yl)phenyl]-N-ethylacetamide (impurity V); N-[3-(3-cyanopyrazolo[1,5-a] pyrimidin-7-yl)phenyl]-N-ethylamine (impurity VI); N-[3-(3-cyano-6-[(E)-3-((N-ethyl-N-acetyl)amino)phenyl-3-oxoprop-1-enyl] pyrazolo[1,5-a]pyrimidin-7-yl) phenyl]-N-ethylacetamide (impurity VII). Structural elucidation of all impurities by spectral data ((1)H NMR, (13)C NMR, MS and IR) and formation of these impurities are discussed in detail.
authors: A.P.L. Research Centre, 313 Bachupally, Hyderabad 500072, India.
authors: Ch
authors: Ch
authors: Bharathi
authors: K Joseph
authors: KJ
authors: Prabahar
authors: Ch S
authors: ChS
authors: Prasad
authors: M Saravana
authors: MS
authors: Kumar
authors: S
authors: S
authors: Magesh
authors: V K
authors: VK
authors: Handa
authors: Ramesh
authors: R
authors: Dandala
authors: A
authors: A
authors: Naidu
mesh_terms: D000081:Acetamides / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D004340:Drug Contamination; D006993:Hypnotics and Sedatives / Q000032:analysis*; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D015394:Molecular Structure; D008970:Molecular Weight; D011743:Pyrimidines / Q000032:analysis* / Q000138:chemical synthesis / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D044366:Transition Temperature
chemical_list: D000081:Acetamides; D006993:Hypnotics and Sedatives; D011743:Pyrimidines; C085665:zaleplon