Novel polyazaheterocyclic systems: Synthesis, antitumor, and antimicrobial activities

The most Recent Compilation of Reactions of Enaminone Derivatives with various Amine Derivatives to Generate Biologically Active Compounds

Heterocyclic derivatives serve as the fundamental components of both natural and synthetic drugs. Enaminones play a crucial role as foundational units in the synthesis of numerous bioactive heterocyclic compounds, including pyrazoles, pyridines, oxazoles, isoxazoles, as well as fused heterocyclic structures like indoles, carbazoles, quinolines, acridines, and phenanthridines. These diverse heterocyclic rings are well-known for their various therapeutic activities, encompassing anticancer, anti-inflammatory, antimicrobial, antidepressant, and antiviral properties. By reacting with nitrogenbased nucleophiles, enaminones can generate bioactive azoles, azines, and their fused systems. This study focuses on the recent advancements in enaminone reactions with (a) nitrogen-based nucleophiles, such as aliphatic amines, derivatives of aniline, heterocyclic amines, hydroxylamine, hydrazine derivatives, guanidine derivatives, urea, and thiourea derivatives, and (b) nitrogen-based electrophiles, such as diazonium salts. These reactions have led to the synthesis of a wide range of bioactive fused heterocyclic compounds from 2010 to the end of 2022.

An overview of the reactions involving azomethine imines over half a decade

Azomethine imines constitute a versatile class of 1,3-dipoles which was used extensively for biologically relevant N-heterocycle synthesis – a five-year recap.

Synthesis of New Furothiazolo Pyrimido Quinazolinones from Visnagenone or Khellinone and Antimicrobial Activity

Substituted-6-methyl-1-thioxo-1,2-dihydro-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-ones (5a,b) were synthesized from condensation of visnagenone (2a) or khellinone (2b) with 6-amino-thiouracil (3) in dimethylformamide or refluxing of (4a) or (4b) in dimethylformamide. Hence, compounds (5a,b) were used as the starting materials for preparing many new heterocyclic compounds such as; furo[3,2-g]pyrimido[1,6-a]quinazoline (6a,b), furo[3,2-g]thiazolo[2',3':2,3]pyrimido[1,6-a]quinazolinone (7a,b), substituted-benzylidene-furo[3,2-g]thiazolo[2',3':2,3]pyrimido[1,6-a]quinazoline-3,5-dione (8a⁻f), 3-oxo-furo[3,2-g]pyrimido[1,6-a]quinazoline-pentane-2,4-dione (9a,b), 1-(pyrazole)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (10a,b), 2-(oxo or thioxo)-pyrimidine-furo[3,2-g]pyrimido[1,6-a]quinazolinone (11a⁻d), 1-(methylthio)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (12a,b), 1-(methyl-sulfonyl)-furo[3,2-g]pyrimido[1,6-a]quinazolinone (13a,b) and 6-methyl-1-((piperazine) or morpholino)-3H-furo[3,2-g]pyrimido[1,6-a]quinazolin-3-one (14a⁻d). The structures of the prepared compounds were elucidated on the basis of spectral data (IR, ¹H-NMR, ¹³C-NMR, MS) and elemental analysis. Antimicrobial activity was evaluated for the synthesized compounds against Gram-positive, Gram-negative bacteria and fungi. The new compounds, furothiazolo pyrimido quinazolines 8a⁻f and 11a⁻d displayed results excellent for growth inhibition of bacteria and fungi.

Advances in 1,2,4-triazepines chemistry

This review reports the chemistry of 1,2,4-triazepines. Heterocyclic 1,2,4-triazepines are mono and fused cycles.

Synthesis of a new series of angiotensin II receptor antagonists and antibacterial agents

2-(Arylmethylenehydrazono)-4,4-diphenyl-1H-imidazol-5(4H)-one 3 underwent regioselective cyclization upon treatment with bromine in acetic acid containing sodium acetate to give the respective 3-substituted-6,6-diphenyl-6,7-dihydro-imidazo[2,1-c][1,2,4]triazole-5-one 4 in overall good yields and not the isomeric structure 5. In addition, compound 4 was synthesized by alternative method via reaction of compound 1 with different acids in acetic acid. The synthesized hydrazone derivatives were screened for their angiotensin II receptor antagonists activity and the results showed promising activity. Also, imidazo[2,1-c][1,2,4]triazole-5-ones 4 were screened for the antibacterial activity and the result revealed that two derivatives have excellent activity.

A Convenient Synthesis of Some New Thiazole and Pyrimidine Derivatives Incorporating a Naphthalene Moiety

The reaction of 2-[1-(naphthalen-2-yl)ethylidene]hydrazinecarbothioamide with hydrazonoyl halides afforded new thiazole derivatives, whilst reaction with compounds containing an activated double bond such as ethoxymethylene-malononitrile and benzylidenemalononitrile yielded the respective pyrimidine derivatives. A 4-thiazolidin-4-one was obtained by reaction of the hydrazinecarbothioamide with ethyl bromoacetate. Subsequent condensation of the thia-zolidinone with aromatic aldehydes afforded the corresponding arylidene derivatives. Treatment of the hydrazinecarbothioamide with dimethyl acetylenedicarboxylate resulted in the formation of a (methoxycarbonylmethylidene) thiazolinone. Reaction of the hydrazinecarbothioamide with 2-chloro-1,3-dicarbonyl compounds gave the respective thiazole derivatives. The structures of the newly synthesised compounds were confirmed by their elemental analysis and spectral data.

A convenient ultrasound-promoted synthesis of some new thiazole derivatives bearing a coumarin nucleus and their cytotoxic activity

Successful implementation of ultrasound irradiation for the rapid synthesis of a novel series of 3-[1-(4-substituted-5-(aryldiazenyl)thiazol-2-yl)hydrazono)ethyl]-2H-chromen-2-ones 5a–h, via reactions of 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene) thiosemicarbazide (2) and the hydrazonoyl halides 3(4), was demonstrated. Also, a new series of 5-arylidene-2-(2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinyl)thiazol-4(5H)-ones 10a–d were synthesized from reaction of 2 with chloroacetic acid and different aldehydes. Moreover, reaction of 2-cyano-N'-(1-(2-oxo-2H-chromen-3-yl)ethylidene)-acetohydrazide (12) with substituted benzaldehydes gave the respective arylidene derivatives 13a–c under the conditions employed. The structures of the synthesized compounds were assigned based on elemental analyses and spectral data. Also, the cytototoxic activities of the thiazole derivative 5a was evaluated against HaCaT cells (human keratinocytes). It was found that compound 5a possess potent cytotoxic activity.

Synthesis and evaluation of the anti-microbial activity of new heterocycles containing the 1,3,4-thiadiazole moiety

A new series of thiadiazole-enaminones 4 were synthesized via reactions of 5-acetyl-1,3,4-thiadiazoles 3 with dimethylformamide-dimethylacetal (DMF-DMA). The simple phenyl substituted thiadiazole-enaminone 4f was used as a synthetic precursor for the preparation of a wide variety of new heterocyclic compounds, including the 5-substituted-1,3,4-thiadiazole derivatives 5, 6, 11, 12 and 13, which were obtained via reactions of 4f with nitrogen nucleophiles. Also, reactions of enaminone 4f with carbon nucleophiles afforded the respective 1,3,4-thiadiazoles 8a–d. In addition, the results of the antimicrobial activities of thiadiazole-enaminones 4 and their precursors 2 and 3 indicate that some members of this series display promising activities against all tested microorganisms.

Hydrazonoyl halides as precursors for new fused heterocycles of 5α-reductase inhibitors

A new series of benzo[6,7]cyclohepta[1,2-d]triazolo[4,3-a]pyrimidines 8a-l was synthesized via reaction of heterocyclic thione 4 or its methyl derivatives 10 with hydrazonoyl halides 5a-l. Also, reaction of compound 4 with a mixture of chloroacetic acid and aromatic aldehyde derivatives gave benzo[6,7]cyclohepta[1,2-d]thiazolo[3,2-a]pyrimidin-3-ones 12-14. The microanalyses and spectral data of the synthesized compounds are in full agreement with their molecular structure. All the newly synthesized products were screened against 5α-reductase and showed activities with good ED(50) for all compounds.