Synthesis of pyrazolo[1,5‐a]‐, 1,2,4‐triazolo[1,5‐a]‐ and imidazo[1,2‐a]pyrimidines related to zaleplon, a new drug for the treatment of insomnia

Abstract

This paper describes the preparation of some pyrazolo[1,5-a]-, 1,2,4-triazolo[1,5-a]-and imidazo[1,2-a]pyrimidines substituted on the pyrimidine moiety by a 4- [(N-acetyl-N-ethyl)amino]phenyl group. A new synthesis of related benzo[h]pyrazolo[1,5-a]-, benzo[h]pyrazolo[5,1-b]-and benzo[h]1,2,4-triazolo[1,5-a]quinazolines is also reported.

Synthesis of a new series of pyrazolo[1,5‐a]pyrimidines structurally related to zaleplon

“…Organic solutions were dried over anhydrous sodium sulphate. Elemental analyses were performed by the micro analytical laboratory of Dipartimento di Chimica, University of Ferrara, and were within ± 0.4% of the theoretical values for C, H and N General Procedure for the Preparation of 3-(Dimethylamino)-1-(substituted)prop-2-en-1-ones (8)(9)(10)(11)(12)(13)(14). To the acetyl compounds 1-7 (1 mL) was added N,N-dimethylformamide dimethyl acetal (1.03 mol eq) and the mixture was heated at 100°C for 18 h. The solvent was removed at reduced pressure and the residue was recrystallized from EtOAc to furnish derivatives 8-14 as solids.…”

Dimethylformamide dimethyl acetal as a building block in heterocyclic synthesis

“…2-Amino-4-[4(N-acetyl-N-ethyl)aminophenyl]pyrimidine (187) was obtained by condensation of enaminone (177i) with guanidine hydrochloride. Enaminone (177i) reacted with 3-amino-1,2,4-triazole to give 1,2,4-triazolo[1,5-a]pyrimidine (188) [32,133] as shown in Scheme 26.…”

“…Refluxing of compound (25) with DMFDMA provided the enaminones (26), which were directly allowed to react with binucleophiles such as substituted guanidine and amino azoles (3-aminopyrazoles, 3-amino-1,2,4-triazole) to give the desired compounds (27a,b) and (28a-d), respectively, as in Scheme 8 [31,32].…”

Synthesis and Biological Evaluation of some Novel Pyrano[2,3-<i>d</i>]Pyrimidine Derivatives

“…Some of them exhibit antihypertensive activity [9], antimalarial [10], analgesic [10,11], and antimicrobial and antiviral evaluation [12,13] properties. Pyrano [2,3-d]pyrimidines are building blocks used to evaluate their antimicrobial activities and various derived natural products [14]. Therefore, for the preparation of these complex molecules large efforts have been directed toward the synthetic manipulation of pyrano [2,3-d]pyrimidine derivatives.…”