title: A facile environment-friendly one-pot two-step regioselective synthetic strategy for 3,7-diarylpyrazolo[1,5-a]pyrimidines related to zaleplon and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines assisted by KHSO₄ in aqueous media.
abstract: 3-Aminopyrazoles required for the synthesis of pyrazolo[1,5-a]pyrimidines were obtained by the reaction of enaminonitriles with hydrazine hydrate. The resulting aminopyrazoles are reacted with formylated acetophenones under reflux at [Formula: see text] assisted by KHSO[Formula: see text] in aqueous media to form regioselectively 3,7-diarylpyrazolo[1,5-a]pyrimidines and 3,6-diarylpyrazolo[1,5-a]pyrimidine-7-amines. X-ray crystallography of selected compounds 5b and 7i further confirmed the regioselective formation of these products.
authors.affiliation: Organic Research Lab., Department of Chemical Science, Assam Don Bosco University, Airport Road-Azara, Guwahati, Assam, 781017, India.
authors.forename: Asem Satyapati
authors.initials: AS
authors.lastname: Devi
authors.affiliation: Organic Research Lab., Department of Chemical Science, Assam Don Bosco University, Airport Road-Azara, Guwahati, Assam, 781017, India.
authors.forename: Shunan
authors.initials: S
authors.lastname: Kaping
authors.affiliation: Organic Research Lab., Department of Chemical Science, Assam Don Bosco University, Airport Road-Azara, Guwahati, Assam, 781017, India. jnvishwakarma@rediffmail.com.
authors.forename: Jai Narain
authors.initials: JN
authors.lastname: Vishwakarma
mesh_terms: D000081:Acetamides / Q000737:chemistry; D000588:Amines / Q000737:chemistry; D006834:Hydrazines / Q000737:chemistry; D008968:Molecular Conformation; D015394:Molecular Structure; D011720:Pyrazoles / Q000138:chemical synthesis*; D011743:Pyrimidines / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: C436945:3-aminopyrazole; D000081:Acetamides; D000588:Amines; D006834:Hydrazines; D011720:Pyrazoles; D011743:Pyrimidines; C029424:hydrazine; C085665:zaleplon
keywords: 3-Aminopyrazole; Michael addition; Pyrazolo[1, 5-a]pyrimidines; Regioselectivity; Zaleplon