Reactions of pyrimidinonethione derivatives: Synthesis of 2-hydrazinopyrimidin-4-one, pyrimido[1,2-a]-1,2,4-triazine, triazolo-[1,2-a]pyrimidine, 2-(1-pyrazolo)pyrimidine and 2-arylhydrazonopyrimidine derivatives

Abstract

6-Aryl-5-cyano-4-pyrimidinon-2-thione derivatives1a-c reacted with ethyl iodide to give the corresponded 2-S-ethylpyrimidin-4-one derivatives2a-c. Compounds2a-c was, in turn, reacted with hydrazine hydrate to give the sulfur free reaction products,3a-c. These reaction products were taken as the starting materials for the synthesis of several newly synthesized heterocyclic derivatives. Reactions with several halogenated ketones, esters, chloroacetic acid and chloroacetamide give pyrimidotriazines8, 12 and15 while their reactions with formic acid, acetic acid and carbon disulfide gave the corresponded triazolopyrimidines17 and21. The reaction with both acetyl acetone and ethylacetoacetate gave the corresponded 2-(3', 5'-dimethyl-1'-pyrazoly) pyrimidine derivatives20a-c and24a-c respectively while the reaction with cinnamonitriles25a-h afforded the corresponded aryl hydrazopyrimidines27a-f. The structures of these reaction products were established based on both elemental analyses and spectral data studies.

Synthesis and antitumor evaluation of some new derivatives and fused heterocyclic compounds derived from thieno[2,3‐b]pyridine: Part 2

“…Compound 11 was utilized for the construction of fiveand six-membered rings that are directly attached to imidazo [1,2-c]pyrimidine nucleus, among which 5hydrazinoimidazo[1,2-c]pyrimidine derivative 11 was stirred with an aqueous solution of sodium nitrite in glacial acetic acid at room temperature [21] to afford tetrazolo [1,5-a]pyrimidine analogue and its azide tautomers 12. [26] This reaction mechanism proceeded via the formation of nonisolable product through the elimination of hydrogen chloride followed by ring closure and removal of an ethanol molecule to give a pyrimidotriazine product that could be enolized to its tautomeric form [26] as illustrated in Figure 1. Besides, characteristic absorption bands of bond stretching vibrations are typical for a tetrazole ring at 1132, 1095, and 1038 cm −1 .…”

“…EtOH, reflux; (v) NaNO 2 /AcOH, stir at rt; (vi) HC (OC 2 H 5 ) 3 , reflux; (vii) ethyl 2-chloroacetoacetate/NaOMe/MeOH, reflux of a strong base. [26] This reaction mechanism proceeded via the formation of nonisolable product through the elimination of hydrogen chloride followed by ring closure and removal of an ethanol molecule to give a pyrimidotriazine product that could be enolized to its tautomeric form [26] as illustrated in Figure 1. Scheme 3 illustrates the synthesis of pyrimidine-2,4dithione derivative 15 that was achieved through the treatment of 3-amino-2-nitrile derivative 1 with carbon disulfide in the presence of hot pyridine as a base and a solvent at the same time.…”

“…Compound (1) was synthesized according to the published procedure, [11] while compounds (8), (10), (23), (26), and (37) were prepared according to our previously published procedures. [19] However, reagents (16a), [29] (16b), [30] and (20) [37] were prepared according to the reported methods.…”

Novel Pyrimidinone Derivatives: Synthesis, Antitumor and Antimicrobial Evaluation

“…22) Alternatively, another approach was achieved by alkylation of compound 4a, followed by treatment of the formed S-alkylated products with hydrazine hydrate to afford a 30% yield of 7a according to reported method. 23) The IR spectra of 7a, c showed two absorption bands at 3320 and 3282 cm H-NMR spectra showed the two characteristic singlets of NH 2 around 7.07 and 7.57 ppm respectively, exchangeable with D 2 O (cf. Experimental).…”

“…1 H-NMR spectra of the latter compounds are characterized by a singlet corresponding to H-3 proton of the triazole ring at δ 9.33, 9.35 and 9.30 ppm, respectively. 23) On the other hand, the reaction of 7a-c with chloroacetyl chloride yielded compounds 9a-c which were separated as hydrochloride salts. 24) IR spectra showed an additional absorption band around 1720 cm −1 corresponding to the new νC=O.…”