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Heterocycles incorporating a pyrimidopyrimidine scaffold have aroused great interest from researchers in the field of medical chemistry because of their privileged biological activities; they are used as anti-bacterial, antiviral, anti-tumor, anti-allergic, antihypertensive, anticancer, and hepatoprotective agents. Therefore, the present study aims to investigate the chemistry of heterocycles incorporating pyrimido[1,6-a]pyrimidine and pyrimido[1,6-c]pyrimidine skeletons and their biological characteristics. The main sections discuss (1) the synthetic routes to obtain substituted pyrimidopyrimidines, pyrimido[1,6-a]pyrimidin-diones, pyrimidoquinazolines, tricyclic, tetracyclic, and binary systems; (2) the reactivity of the substituents attached to the pyrimidopyrimidine skeleton, including thione and amide groups, nucleophilic substitutions, condensations, ring transformations, and coordination chemistry; (3) compounds of this class of heterocycles containing a significant characteristic scaffold and possessing a wide range of biological characteristics.

A newly synthesized ortho-amino thio-phenol modified flax fibers (OATP-MFF) were prepared in two subsequent steps; at first flax fiber was pretreated with sodium periodate. Then the pretreated fibers were condensed with ortho-amino thio-phenol to form the modified flax fiber(OATP-MFF). The OATP-MFF was characterized by (FTIR) Fourier transform infrared spectra, SEM and energy-dispersive X-ray Spectroscopy (EDX). The newly synthesized OATP-MFF chelating fibers were utilized for selective separation of Cu(II) from aqueous solution by adsorption methodology. The effects of pH, the initial concentration of metal ions, the adsorbent dosage, the interfering ions and the contact time on the adsorption capacity of OATP-MFF chelating fibers were investigated. The maximum adsorption capacity of Cu(II) at the optimum conditions was 92 mg/g. The adsorption process fitted well the second-order model kinetic of. The chemical (adsorption) reaction is the rate-limiting step that was proved from the kinetic model.

The present study provides an overview of the chemistry and biological significance of pyrimido[4,5-d]pyrimidine and pyrimido[5,4-d]pyrimidine analogs as types of bicyclic [6 + 6] systems. The main sections include: (1) synthesis methods; (2) the reactivities of the substituents linked to the ring carbon and nitrogen atoms; and (3) biological applications. A discussion demonstrating the proposed mechanisms of unexpected synthetic routes is intended. The aim of this study is to discuss the synthetic significance of the titled compounds and to establish the biological characteristics of this class of compounds as studied to date, where the compounds have been applied on a large scale in the medical and pharmaceutical fields. This survey will help researchers in the fields of synthetic organic and medicinal chemistry to undertake and improve new approaches for the construction of new standard biological components.

4-Formylphenyl benzoate was utilized as a versatile precursor for the construction of new series of heterocyclic scaffolds that contain thiazole and thiazolidin-5-one rings. The antibacterial activity of these scaffolds against two types of bacteria was screened and most of them exhibited good activity. Among the synthesized thiazole derivatives, compounds 5, 6, and 8a showed antibacterial activity close to the standard chemotherapeutic (Ampicillin).

Heterocycles incorporating a pyrimidopyrimidine scaffold have aroused great interest from researchers in the field of medical chemistry because of their privileged biological activities; they are used as anti-bacterial, antiviral, anti-tumor, anti-allergic, antihypertensive, anticancer, and hepatoprotective agents. Therefore, the present study aims to investigate the chemistry of heterocycles incorporating pyrimido[1,6

The present study provides an overview of the chemistry and biological significance of pyrimido[4,5

The chemical structure of pyrazole-1-carbothioamide derivative 1 was modified through building a thiazole moiety to synthesize derivatives of thiazolyl pyrazolin-5-one. The reaction of 1 with phenacyl bromide furnished the conforming thiazolyl pyrazole derivative 2, which upon base-catalyzed reaction with benzyl isothiocyanate afforded thiazolyl 4-(benzylthiocarbamoyl)-2-pyrazolin-5-one derivative 3. The diazo-coupling reaction of 2 with diazotized 4-aminoacetophenone afforded the conforming thiazolyl 4-(p-acetylphenylhydrazono)-2-pyrazolin-5-one derivative 4. The synthesized thiazolyl pyrazolin-5-one derivatives were utilized as antioxidant additives for lubricating oil. The oxidation stability study revealed that the tested compounds showed good antioxidant activities. The efficiency of the tested antioxidant additives decreases according to the order: compound 2 > compound 4 > compound 3 > compound 1.

This review describes a literature survey of 1,3,5-triazepines. The investigated heterocycles were the monocyclic and fused 1,3,5-triazepines. The different sections of the paper cover: theoretical methods, spectroscopy aspects, thermodynamic aspects, synthesis and reactions of the monocyclic and fused heterocycles incorporated into the 1,3,5-triazepine moiety. The biological evaluation of the target compounds are also described as well as their synthetic applications. The reaction mechanisms are discussed.

This review reports the literature survey of 1,2,4-triazepines. The investigated heterocycles are monocyclic and fused 1,2,4-triazepines. The different sections cover theoretical calculations of conformations and tautomerism, and synthesis and reactions of monocyclic and fused heterocycles incorporating 1,2,4-triazepines. The biological evaluation of the target compounds and related compounds is described, as well as the synthetic applications. The reaction mechanisms are discussed. The bibliography includes 152 references.

Benzoxazinone 2 was prepared and reacted with formamide, acetamide, some primary aromatic amines and heterocyclic amines giving the corresponding quinazolone derivatives 3–15 respectively. The reaction of benzoxazinone 2 with hydrazine hydrate and phenyl hydrazine was also studied. Representative compounds of the synthesized products were evaluated as antioxidants and corrosion inhibitors for gasoline engine lubricating oil. The highest antioxidant activities were obtained with compounds 10–15. The optimum concentration recommended for these new additives was found to be 0.1g for 1L of oil for compounds 13–15. In addition, some of the highly effective antioxidant additives, namely 10–15, were thermally analyzed by using thermogravimetric analysis (TGA) and differential thermal gravimetric analysis (DTGA) techniques and the results indicated that compounds are thermally stable and could be used under thermal conditions. Moreover, a comparison of the oxidation stability between the tested oil containing the prepared products and lubricating oil containing commercial additives was also studied.

Oxazolone derivative 2 was utilized as a key intermediate for synthesis of some new oxazolone and imidazolone derivatives. Reaction of oxazolone derivative 2 with diamines under different conditions afforded the corresponding imidazolone derivatives 3–8, respectively. Moreover, oxazolone 2 reacted with some heterocyclic amines in glacial acetic acid giving the corresponding imidazolone derivatives 9–14, respectively. Cyclocondensation of thiosemicarbazide with compound 2 in dry pyridine afforded compound 15. Addition of secondary amines to olefin double bond of compound 2 gave the corresponding addition products 16–19, respectively. Michael addition of compound 2 with some active methylene compounds afforded oxazolone derivatives 20–23, respectively. These prepared products were evaluated as antioxidant and corrosion inhibitors for gasoline lubricating oil and compounds 6a–c, 10 and 15 exhibited the highest antioxidant and anticorrosive activities. The effect of concentration of additives was studied to recommend the optimum concentration to be used. The results showed, for additive 15, 0.1 g for 1 L oil was the more effective concentration. Measurements for thermal analysis and of surface tension of oil after oxidation were also carried out.

Oxazolone derivative 2 was utilised as a key intermediate for the synthesis of some new imidazolone deriva- tives. Reaction of 2 with p-aminoacetophenone in the presence of acetic acid containing catalytic amount of freshly fused sodium acetate gives the corresponding imidazolone derivative 3 which on reaction with diethyl oxalate in the presence of granulated sodium metal afforded the corresponding imidazolone derivative 4. Condensation of compound 3 with some aromatic aldehydes afforded the corresponding cinnamoylphenyl derivatives 5a-c, respectively. Besides, compounds 5a-c reacted with hydrazine hydrate in boiling ethanol and yield the corresponding 4-arylidene-1- (p-(5-aryl-2- pyrazolin-3-y1) phenyl)-2-phenyl-2-imidazolin-5-ones 6a-c, respectively. Moreover, refluxing of compounds 5a-c with both ethylcyanoace- tate and/or malononitrile in ethanol and ammonium acetate afforded 7a-c and 8a-c, respectively. Claisen reaction of 3 with ethylacetate gives the corresponding imidazolone derivative 9 which on reaction with thiourea in ethanol afforded the cor- responding thienopyrimidine derivative 10. On the other hand, reaction of oxazolone 2 with both ethyl p-aminobenzoate and anthranilic acid in glacial acetic acid and freshly fused sodium acetate has been also studied. Structures of the newly synthesized compounds were established by elemental analysis and spectral data. Representative compounds of the synthe- sized products were tested and evaluated as antifungal and antimicrobial agents. Most of compounds exhibited good activi- ties, where 3, 5b, 5c, 6a, 7b, 7c, 8a, 9, 11, 13 and 14 exhibited good activities against Bacillus Thuringenesis and Klebseilla Pneumonia, while compounds 3, 4, 6a, 6b, 6c, 7c, 8a, 8c, 11, 12 and 16 exhibited good activities against Trichoderma

2-(4-Toluenesulphonyloxy phenyl)-3,1-benzoxazine-4-one 2 was prepared and reacted with some nitrogen nucleophiles, e.g., ammonia, o-phenylendiamine, some heterocyclic amines, hydrazine hydrate and hydroxylamine hydrochloride and sulphur nucleophile, e.g., phosphorous pentasulphide. Structures of the newly synthesized compounds were established by elemental analysis and spectral data. All new prepared compounds were subjected to antimicrobial activity evaluation where compounds, 8, 9, 10 and 18 exhibited good activities against Bacillus Thuringenesis and 5, 10, 11, 14, 15, 17 and 18 exhibited good activities against Klebseilla Pneumonia. On the other hand, the results for antifungal activities revealed that, compounds 5, 6, 7, 16 and 17 exhibited good activities against Trichoderma Herzianum and Trichoderma Virdi.