Synthesis of substituted 3,4-dihydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones and pyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones by the Biginelli reaction with 3,5-Di-<Emphasis Type="Italic">tert</Emphasis>-butyl-4-hydroxybenzaldehyde

Three-component acid-catalyzed cyclocondensation of 3,5-di-tret-butyl-4-hydroxybenzaldehyde with urea and ethyl acetoacetate or α-nitroacetophenone (Biginelli reaction) under homogeneous conditions gave the corresponding 5-substituted 3,4-dihydropyrimidin-2(1H)-ones having in position 4 of the heteroring an aryl substituent with sterically shielded hydroxy group. The condensation catalyzed by inorganic salts (Fe³⁺, Co²⁺, Zn²⁺, Li⁺) was successful only with ethyl acetoacetate as initial methylene-active component. Under analogous conditions, acetophenone and 4-fluoroacetophenone gave rise to 4,6-diarylpyrimidin-2(1H)-ones which are capable of undergoing phenol-quinonemethide tautomerism.     

Enantioselective microbial synthesis of (<Emphasis Type="Italic">S</Emphasis>)-7,8-difluoro-3,4-dihydro-3-methyl-2<Emphasis Type="Italic">H</Emphasis>-[1,4]benzoxazine

New strains of Rhodococcus erythropolis 25 and Microbacterium paraoxydans 20-11c actinobacteria were used to obtain (S)-7,8-difluoro-3,4-dihydro-3-methyl-2H-[1,4]benzoxazine (99.6% ee) by enantioselective microbial hydrolysis of the corresponding racemic N-acetyl derivative.     

Chemistry of 2-ylidenefuran-3(2<Emphasis Type="Italic">H</Emphasis>)-ones: XIX. Reaction of 5-aryl-2(oxoylidene)furan-3(2<Emphasis Type="Italic">H</Emphasis>)-ones with carboxylic acid hydrazides

2-[2-(4-Chlorophenyl)-2-oxoethylidene]-5-phenylfuran-3(2H)-one and methyl (5-aryl-3-oxo-2,3-dihydrofuran-2-ylidene)acetates react with carboxylic acid hydrazides to give the corresponding 3-substituted 2-acyl-6-aryl-3-hydroxy-2,3-dihydropyridazin-4(1H)-ones. Specificities of the product structure are discussed.     

Synthesis and calming activity of helicid derivatives containing the 3,4-dihydropyrimidin-2(<Emphasis Type="Italic">H</Emphasis>)-one and 3,4-dihydropyrimidine-2(<Emphasis Type="Italic">H</Emphasis>)-thione moiety

A series of novel helicid derivatives containing 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidine2(1H)-thione moiety (3a–3f and 4a–4f) were synthesized starting from helicid. The structure of the new compounds were characterized by ¹H NMR, IR and HR-MS spectra. The sedative-hypnotic activities of the target compounds were evaluated using the test of spontaneous locomotor activity in mice. All of the derivatives produced moderate to high activities; in particular, compound 4a presented the most potent sedative-hypnotic effect in comparison to the other derivatives, and derivatives 3a, 3c, 3d, 3e and 3f also showed potent activities.     

Reactions of 3-Aroylpyrrolo[1,2-<Emphasis Type="Italic">a</Emphasis>]quinoxaline-1,2,4(5<Emphasis Type="Italic">H</Emphasis>)-triones with 2,3-Dihydrofuran and 3,4-Dihydro-2<Emphasis Type="Italic">H</Emphasis>-pyran

3-Aroylpyrrolo[1,2-a]quinoxaline-1,2,4(5H)-triones reacted with 2,3-dihydrofuran and 3,4-dihydro-2H-pyran to give mixtures of the corresponding hetero-Diels–Alder (furo- and pyrano[3″,2″: 5′,6′]pyrano- [4′,3′: 2,3]pyrrolo[1,2-a]quinoxalines) and Michael adducts (furyl- and pyranylpyrrolo[1,2-a]quinoxalines).     

Regioselective synthesis of polyfluoroalkyl-substituted 7-(1<Emphasis Type="Italic">H</Emphasis>-1,2,3-triazol-1-yl)-6,7-dihydro-1<Emphasis Type="Italic">H</Emphasis>-indazol-4(5<Emphasis Type="Italic">H</Emphasis>)-ones

3-Polyfluoroalkyl-6,6-dimethyl-7-(1H-1,2,3-triazol-1-yl)-6,7-dihydro-1H-indazol-4(5H)-ones were synthesized with high regioselectivity by 1,3-dipolar cycloaddition of terminal alkynes (phenylacetylene, hex- 1-yne, hept-1-yne, and but-3-yn-1-ol) to 7-azido-6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol-4(5H)-ones which were prepared by bromination of 6,6-dimethyl-3-polyfluoroalkyl-6,7-dihydro-1H-indazol- 4(5H)-ones with N-bromosuccinimide in anhydrous carbon tetrachloride, followed by treatment of the corresponding 7-bromo derivatives with sodium azide.     

Synthesis and biotests of 2-aryl-5-arylmethylidene-substituted 1,3-oxazol-5(4<Emphasis Type="Italic">H</Emphasis>)-ones and <Emphasis Type="Italic">N</Emphasis>-methyl-3,5-dihydro-4<Emphasis Type="Italic">H</Emphasis>-imidazol-4-ones as combretastatin A-4 analogs

A series of 2-aryl-5-arylmethylidene-1,3-oxazol-5(4H)-ones and 2-aryl-5-arylmethylidene-N-methyl-3,5-dihydro-4H-imidazol-4-ones was synthesized as structural analogs of combret- astatin A-4 (a compound possessing antitumor activity). (5Z)-5-[(4-Methoxyphenyl)methyl-idene]-3-methyl-2-(4-methylphenyl)-3,5-dihydro-4H-imidazol-4-one was found to exhibit the highest cytotoxicity against cells of human A549 lung carcinoma line (EC₅₀ = 6±0.8 μmol L^?1).     

Substituted Butanolides and Butenolides: XVII. Substituted 3-(Furan-2-ylmethylidene)furan-2(3<Emphasis Type="Italic">H</Emphasis>)-ones and 3-(Furan-2-ylmethylidene)dihydrofuran-2(3<Emphasis Type="Italic">H</Emphasis>)-ones

A number of furan-2-ylmethylidene-substituted lactones were synthesized by condensation of 5-alkylfuran-2(3H)-ones and 4-alkyldihydrofuran-2(3H)-ones with 5-substituted furan-2-carbaldehydes. The reactivity of furan-2(3H)-ones was higher than that of furan-2(5H)-ones due to formation of intermediate conjugated anion. The condensation of 4-alkyldihydrofuran-2(3H)-ones with furan-2-carbaldehydes required more severe conditions than the condensation with furan-2(3H)-ones. The substituent in the furan ring affects the reaction time and yield.     

<Emphasis Type="Italic">S</Emphasis>-functional derivatives of 3,4-dihydro-2<Emphasis Type="Italic">H</Emphasis>-1,4-thiasilines

The first cyclic unsaturated S-functional derivatives of 4,4-diphenyl-3,4-dihydro-2H-1,4-thiasiline, S-oxide, S,S-dioxide, and S-sulfonimide, were prepared. Oxidation of the hydrolytically less stable 4,4-dimethyl-3,4-dihydro-2H-1,4-thiasiline leads to the corresponding sulfoxide and sulfone along with the ring opening products, siloxanes containing the sulfoxide or sulfonyl group.     

Carboxamides of Dihydropyridin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones

Summary. 3-Carboxamides and 3-carboxanilides of 6-alkyl and 6-aryldihydropyridin-2(1H)-ones have been prepared via different reaction pathways. All synthesized amides show hydrogen bonds in their NMR spectra. The 4-hydroxy compounds were obtained as a mixture of tautomers. Their configurations were elucidated by NMR experiments.Received December 16, 2002; accepted December 20, 2002 Published online June 2, 2003     

Alkylation of 2-(hydroxyimino)-5<Emphasis Type="Italic">H</Emphasis>-[1,3]thiazolo[3,2-<Emphasis Type="Italic">a</Emphasis>]-pyrimidin-3(2<Emphasis Type="Italic">H</Emphasis>)-ones

Alkylation products were obtained from ethyl 2-(hydroxyimino)-7-methyl-3-oxo-5-aryl-2,3- dihydro-5H-[1,3]thiazolo[3,2-a]pyrimidin-6-carboxylates at the treatment with alkyl halides, dimethyl sulfate, and diazomethane. Diazomethane alkylated the initial substrate at the oxygen atom of the carbonyl group of the thiazolidine fragment, the other reagents, at the oxygen atom of the hydroxyimino group.     

Reaction 5-(Arylmethylidene)pyrimidine-2,4,6(1<Emphasis Type="Italic">H</Emphasis>,3<Emphasis Type="Italic">H</Emphasis>,5<Emphasis Type="Italic">H</Emphasis>)-triones with L-Proline and Aldehydes

Boiling in toluene of 5-(arylmethylidene)pyrimidine-2,4,6(1H,3H,5H)-triones with L-proline and aldehyde led to the formation of previously unknown substituted 1′-arylhexahydro-1H-spiro[pyrimidine-5,2′-pyrrolysine]-2,4,6(1H,3Н,5Н)-triones.     

First catalyst- and solvent-free synthesis of 3,4-dihydropyrimidin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones and -thiones

A completely green and environmentally benign Biginelli synthesis of 3,4-dihydropyrimidine-2(1H)-ones and -thiones by one-pot three-component reaction of aromatic aldehydes with ethyl acetoacetate and urea or thiourea without any catalyst under solvent-free conditions is described.     

A new 3,4-dihydroisocoumarin isolated from <Emphasis Type="Italic">Botryosphaeria</Emphasis> sp<Emphasis Type="Italic">.</Emphasis> F00741

A new 3,4-dihydroisocoumarin, named botryoisocoumarin A (1), was obtained from the fermentation culture of Botryosphaeria sp. F00741, together with two known ones, 3,8-dihydroxy-3-methylisochroman-1-one (2) and 4,8-dihydroxy-3-methylisochroman-1-one (3). Their structures were elucidated by spectroscopic analyses, including 1D and 2D NMR experiments and ESI mass spectrometry, and by comparison with those reported. Compound 1 was evaluated for its antitumor and antimicrobial activities in vitro.     

Synthesis of (<Emphasis Type="Italic">S</Emphasis>)-(+)-6-aryl-3-acetyl-6-trifluoromethyl-5,6-dihydropyridin-2(1<Emphasis Type="Italic">H</Emphasis>)-ones

(S)-(+)-4-Amino-4-aryl-5,5,5-trifluoropentan-2-ones reacted with ethyl acetoacetate and ethyl trifluoroacetoacetate to give (S)-(+)-6-aryl-3-acetyl(or trifluoroacetyl)-6-trifluoromethyl-5,6-dihydropyridin-2(1H)-ones.     

Microwave assisted synthesis of substituted (<Emphasis Type="Italic">Z</Emphasis>)-2-{[1-phenyl-3-(thiophen-2-yl)-1<Emphasis Type="Italic">H</Emphasis>-pyrazol- 4-yl]methylene}benzofuran-3(2<Emphasis Type="Italic">H</Emphasis>)-ones and their antimicrobial activity

Aurones, pyrazole and thiophene scaffolds are known for their potential antimicrobial activity. Herein, we have synthesized hybrid compounds containing three substituted (Z)-2-{[1-phenyl-3-(thiophen-2-yl)- 1H-pyrazol-4-yl]methylene}benzofuran-3(2H)-ones that had been produced from substituted (E)-1-(2-hydroxyphenyl)- 3-[1-phenyl-3-(thiophen-2-yl)-1H-pyrazol-4-yl]prop-2-en-1-ones in high yields. All synthesized compounds were tested in vitro for their antimicrobial activity. Several of those demonstrated promising activity against some fungal and bacterial strains.     

One-pot synthesis of 5,6-disubstituted 3<Emphasis Type="Italic">H</Emphasis>-pyrrolizines organocatalyzed by piperidinium acetate

The organocatalyst, piperidinium acetate formed in situ, was utilized as an efficient catalyst for one-pot synthesis of 5,6-disubstituted 3H-pyrrolizines with halogen (Cl, Br), methoxy and ethyl ester groups. Absorption and emission spectra properties were also compared in dichloromethane, toluene, methanol, and DMSO. Electronic spectra were altered slightly by these substituents, which can be well explained by TD-DFT calculations. And the selected four orbital energies indicated that electrons transited smoothly from the pyrrolizine ring to the indole unit.     

Isomeric form and proton localization in (9<Emphasis Type="Italic">E</Emphasis>)-phenanthrene-9,10-dione[(1<Emphasis Type="Italic">Z</Emphasis>)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2<Emphasis Type="Italic">H</Emphasis>)-ylidene]hydrazonium bromide

(9E)-Phenanthrene-9,10-dione[(1Z)-3,3-dimethyl-3,4-dihydroisoquinolin-1(2H)-ylidene]hydrazonium bromide (LH)Br (I) was synthesized. The models of protonated forms of the LH⁺ cation were calculated by quantum-chemical methods, and their relative stability was estimated. The crystal structure of compound I was determined by X-ray diffraction analysis. Compound I is built according to the cation-anion type (the mobile protons are located at the nitrogen atoms). The cation exists in the s-cis,cis-isomeric form stabilized by two cyclic hydrogen bonds. The π-electron density is localized on the multiple bonds N(1)-C(1) (1.292(4) Å) and N(3)-C(12) (1.294(4) Å). the spectroscopic characteristics (IR and electronic absorption spectra) of compound I are obtained.