Palladium catalyzed C-C coupling reactions of 3,5-dichloro-4H-1,2,6-thiadiazin-4-one

Palladium catalyzed Suzuki-Miyaura, Stille, and Sonogashira coupling reactions are reported for the electron-deficient heterocyclic scaffold 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (1). Furthermore, 3,5-di(thien-2-yl)-4H-1,2,6-thiadiazin-4-one (7m) is further elaborated to afford the tetrathienyl 3,5-bis[(2,2'-bithien)-5-yl]-4H-1,2,6-thiadiazin-4-one (9). All compounds are fully characterized.     

The reaction of imidazole with 2-phenyl,4-chloromethylene-oxazol-5-one

The displacement of chlorine from 2-phenyl,4-chloromethylene-oxazol-5-one by imidazole does not lead to carbon-carbon bond formation as previously reported, but involves attack by nitrogen leading to 2-phenyl,4-(imidazol-1-yl)methylene-oxazol-5-one.     

Synthesis of phenoxyquinolin-4(1H)-one through copper(II)-mediated cross-coupling of phenylboronic acid and hydroxyquinolin-4(1H)-one

A synthetic method to prepare novel phenoxyquinolin-4(1H)-one compounds via cross-coupling of hydroxyquinolin-4(1H)-one with a variety of phenylboronic acids is reported. The reaction is mediated by copper(II) acetate at room temperature in air and is tolerant of several functional groups on the phenylboronic acids.     

Isothiazoles VI: 4,5-dihaloisothiazolidin-3-one 1-Oxides

A useful and facile procedure for preparing 4,5-dihaloisothiazolidin-3-one 1-oxides is reported. Chlorination or bromination of various 4-isothiazolin-3-one 1-oxides yielded the title compounds.     

Synthesis and antifungal bioactivities of 3-alkylquinazolin- 4-one derivatives

A simple, efficient, and general method has been developed for the synthesis of various 3-alkylquinazolin-4-one derivatives from quinazolin-4-one treated with alkyl bromides under phase transfer catalysis condition. The structures of the compounds were characterized by elemental analysis, IR, (1)H-NMR and (13)C-NMR spectra. Title compound 6-bromo-3-propylquinazolin-4-one (3h) was found to possess good antifungal activity.     

The reaction of 2,6-diphenyl-2,3,5,6-tetrahydro-4H-thiopyran-4-one with sulfuryl chloride

2,6-Diphenyl-2,3,5,6-tetrahydro-4H-thiopyran-4-one was treated with one, two, and three equivalents of sulfuryl chloride in the presence of pyridine to give the dihydrothiopyranone 2 , the 3-chlorodihydrothiopyranone 3 , and the triehlorotetrahydrothiopyranone 4 , respectively. Compound 4 was converted to 3-chloro-2,6-diphenyl-4H-thiopyran-4-one by pyrolysis and to 3-hydroxy-2,6-diphenyl-4H-thiopyran-4-one on treatment with alcohols. Several pyrylium dyes were prepared from the latter compounds.     

A practical approach to new (5Z) 2-alkylthio-5-arylmethylene-1-methyl-1,5-dihydro-4H-imidazol-4-one derivatives

A practical protocol for the preparation of (5Z)-2-alkylthio-5-arylmethylene-1-methyl-1,5-dihydro-4H-imidazol-4-one derivatives is reported. The new compounds were obtained in good yield and stereoselectivity in two steps, namely a solvent-free Knoevenagel condensation under microwave irradiation, followed by an S-alkylation reaction with various halogenoalkanes.     

Synthesis of 3-amino-5H-pyrimido[5,4-b]indol-4-one derivatives

Starting with ethyl 3-aminoindole-2-carboxylate, the synthesis of 3-amino-5H-pyrimido[5,4-b]indole-2,4-dione 5 , 3-amino-5H-pyrimido[5,4-b]indol-4-one 10 and some related compounds is described. Preliminary results about the inhibition of platelet aggregation by these compounds is reported.     

The electronic structure of 4H-pyran-4-one and its sulfur analogues

The electronic structure of 4-H-pyran-4-one and its sulfur analogues were studied using ab initio wave-functions. Bond lengths and overlap populations suggest low aromaticity for this group of compounds. Examination of Jorgensen plots of the lowest π orbitals of I--IV leads to the aromaticity order 4H-thiopyran-4-thione (IV) > 4H-thiopyran-4-one (II) > 4H-pyran-4-thione (III) > 4H-pyran-4-one (I). The effects of including d orbitals were studied using the 3-21G, 3-21G* (6d), and 3-21G* (5d) basis sets. Optimized bond lengths, vibrational frequencies, ionization energies, and dipole moments were also obtained, and results for different basis sets were compared.     

Antimicrobial Activity and DFT Studies of a Novel Set of Spiropyrrolidines Tethered with Thiochroman-4-one/Chroman-4-one Scaffolds

A novel series of 14 spiropyrrolidines bearing thiochroman-4-one/chroman-4-one, and oxindole/acenaphthylene-1,2-dione moieties were synthesized and characterized by spectroscopic techniques, as well as by three X-ray diffraction studies, corroborating the stereochemistry. Quantum chemical calculations studies, using the DFT approach, were performed to rationalize the stereochemical outcome. These N-heterocycles were evaluated for their antibacterial and antifungal activities against some pathogenic organisms. Several compounds displayed moderate to excellent activity towards the screened microbe strains in the study compared to Amoxicillin (AMX), Ampicillin (AMP), and Amphotericin B. Furthermore, a structural activity relationship (SAR) was established considering the synthesized compounds. Pharmacokinetic studies reveal that these derivatives exhibit an acceptable predictive ADMET profile (Absorption, Distribution, Metabolism, Excretion and Toxicity) and good drug-likeness.     

Synthesis and Antifungal Activity of Novel Quinazolin-4(3H)-one Derivatives

A novel group of 6-iodoquinazolin-4(3H)-one derivatives was prepared starting from 6-iodo-2-ethoxy-4H-3,1-benzoxazin-4-one (3) via action of various nitrogen nucleophiles such as primary and secondary amines, hydrazine hydrate, and its derivatives. The 3-amino-2-hydrazinyl-6-iodoquinazolin-4(3H)-one (15) was used as a key starting material to prepare new heterocyclic compounds. The structures of all synthesized compounds were inferred from the infrared, mass spectral, and ¹H NMR spectral data as well as elemental analysis. The fungicidal activities of the target compounds were preliminarily evaluated.     

Synthesis of 1,7-Bis(4-hydroxyphenyl)hepta-4E,6E-dien-3-one

Diarylheptanoids, most of which appearing in the areas of anti-inflammatory, anti-oxidative, super-oxide scavenging and anti-hepatotoxic effects, constitute a distinct group of metabolites of natural plants characterized by two aromatic rings linked by a linear seven aliphatic chain. We have investigated this kind of compounds and made some progress.[1]1,7-Bis(4-hydroxy-phenyl)hepta-4E,6E-dien-3-one (1) was firstly isolated from the seeds of Alpinia blepharocalyx.[2] So far the synthesis of the compound has not been reported yet. Herein, we report the synthesis of compound 1. The synthetic route is outlined in Scheme 1.     

Reaction of 4-iminothiazolidin-2-one with acetylacetone

By the reaction of acetylacetone and arylazoacetylacetones with 4-iminothiazolidin-2-one thiazolo[4,5-b]pyridines were obtained in good yields. Optimum reaction conditions were chosen and some properties of compounds obtained were studied.     

4-Halogeno-1,1,1-trifluorobut-3-yn-2-one [4+2] cycloadducts and their cross-coupling with organozinc compounds

The reactions of 4-chloro-1,1,1-trifluorobut-3-yn-2-one and 4-bromo-1,1,1-trifluorobut-3-yn-2-one with conjugated dienes afford [4+2] cycloadducts in high yields. The halogen atom in the products is readily replaced by a (het)aryl residue in the cross-coupling with organozinc compounds.     

Microwave synthesis,characterization and antimicrobial study of new pyrazolyl-oxopropyl-quinazolin-4(3H)-one derivatives

Heterocyclic compounds containing pyrazolyl-oxopropyl-quinazolin-4(3H)-one are reported to possess significant biological activity. Syntheses of 6-bromo-2-(3-chloro-2-oxopropyl)-3-(4-fluorophenyl)quinazolin-4(3H)-one 2 6-bromo-3-(4-fluorophenyl)-2-(3-hydrazinyl-2-oxopropyl)quinazolin-4(3H)-one 3 and 6-bromo-2-(3-(3-(4-(1-(2-chlorophenyl)-3-methyl-1H-pyrazol-5(4H)-ylideneamino)phenyl)-5-(substituted phenyl)-4,5-dihydro-1H-pyrazol-1-yl)-2-oxopropyl)-3-(4-fluorophenyl)quinazolin-4(3H)-one 5a–j using microwave irradiation have been described. These compounds have been characterized on the basis of the UV, IR, ¹H NMR, ¹³C NMR, Mass and elemental analysis. Compounds have been evaluated for their antimicrobial activity.     

Condensation of 5-hydroxy-2-methyl-4<Emphasis Type="Italic">H</Emphasis>-pyran-4-one with arylglyoxals. Synthesis and properties of 2-aryl-1-(3-hydroxy-6-methyl-4-oxo-4<Emphasis Type="Italic">H</Emphasis>-pyran-2-yl)ethane-1,2-diones

A convenient method was developed for the synthesis of previously unknown 1,2-diketones, based on the condensation of 5-hydroxy-2-methyl-4H-pyran-4-one with arylglyoxals. The study demonstrated the possibility of using these compounds to synthesize nitrogen-containing hetero cyclic systems bearing the 3-hydroxypyran-4-one moiety.     

Synthesis of 1,2-benzisothiazolin-3-ones by ring transformation of 1,3-benzoxathiin-4-one 1-oxides

1,2-Benzisothiazolin-3-ones were synthesized from 1,3-benzoxathiin-4-one 1-oxides by means of a nonhazardous and inexpensive method. The 1,3-benzoxathiin-4-one 1-oxides were prepared by oxidation of 1,3-benzoxathiin-4-ones with hydrogen peroxide in the presence of a catalyst. Attack of amines on the carbonyl groups of the 1,3-benzoxathiin-4-one 1-oxides and subsequent elimination of carbonyl compounds likely produced sulfenic acids, which then underwent ring closure to afford the 1,2-benzisothiazolin-3-ones.     

Synthesis of 1,2,3-benzotriazin-4-one derivatives containing spirocyclic indoline-2-one moieties and their nematicidal evaluation

To discover new chemotypes of nematicides with proper toxicological profiles, a series of novel 1,2,3- benzotriazin-4-one derivatives were synthesized and further bioevaluated. The bioassay results showed that most of the synthesized compounds were endowed with moderate to good control efficacy against Meloidogyne incognita at 10.0 mg/L in vivo. Among them, compounds 6k and 6p displayed 100% inhibitory activities at this concentration, which implied that they could be used as lead compounds for promising nematicides.     

Synthesis and herbicidal activity of 5-(4-hydroxybenzyl)-2-thioxoimidazolidin-4-one esters

A series of novel 5-(4-hydroxybenzyl)-2-thioxoimidazolidin-4-one esters were synthesized under mild conditions by the reaction of 5-(4-hydroxybenzyl)-2-thioxoimidazolidin-4-one and carboxylic acids with DCC and DMAP as the promoters. Their structures were confirmed by 1H-NMR, IR, ESI-MS and elemental analysis. The preliminary bioassy results indicated that some of compounds exhibit good herbicidal activity against Zea mays, Triticum aestivum and Arabidopsis thaliana. The further greenhouse test showed that compounds 6-16 and 6-28 have 60%, 50% and 50% efficacy against Stellaria media, Echinochloa crus-galli and Setaria viridis at 1,000 g/ha, respectively.     

Regio- and stereochemical features of the reactions of 1,2,5-trimethylpiperidin-4-one with chalcone

The reactions of N-substituted piperidin-4-ones with benzylideneacetophenone, resulting in the synthesis of a number of heterocyclic 1,5-dicarbonyl compounds, were studied. 1,2,5-Trimethylpiperidin-4-one enters into cascade-type chalcone addition accompanied by intramolecular aldol condensation giving rise to the 3-azabicyclo[3.3.1]nonane system. The conformations of the 1,5-dicarbonyl compounds and azabicyclononanes synthesized were determined; the regio- and stereochemical features of the reactions of 1,2,5-trimethylpiperidin-4-one with chalcone were studied.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2693–2697, December, 2004.