Transformations of 3-(1,3-dioxobutan-1-yl)-3H-chromen-2-one during the action of bromine

It was established that the direction of the reaction of 3-(1,3-dioxobutan-1-yl)-2H-chromen-2-one with bromine depends on the conditions under which it is carried out. In acidic media carbocyclization occurs with the formation of dihydroxanthylium bromide or hydroxyxanthene; in chloroform enolization of the carbonyl group with subsequent bromination and heterocyclization to substituted pyranochromene with the participation of the benzopyran-2-one fragment occurs.     

Comparison of reactivities of 1- and 4-oxotetrahydrocarbazoles in reactions with nucleophilic and electrophilic reagents

The half-wave potentials of polarographic reduction of the carbonyl group in unsubstituted and N-methyl- and N-phenylsulfonyl-substituted 1- and 4-oxotetrahydrocarbazoles and their reactivities in reactions with nucleophilic (NaBH₄, malonodinitrile, and cyanoacetamide) and electrophilic (DMF dimethyl acetal) reagents were compared. 4-Oxotetrahydrocarbazoles are much less reactive than 1-oxotetrahydrocarbazoles. __________ Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1832–1836, August, 2005.     

Synthesis of 3-(2-(4,5-Dihydro-3,5-diphenylpyrazol-1-yl)thiazol-4-yl)-2H-chromen-2-one Derivatives via Multicomponent Approach

An efficient synthesis of 3-(2-(4,5-dihydro-3,5-diphenylpyrazol-1-yl)thiazol-4-yl)-2H-chromen-2-one derivatives by a simple, atom-economical, and multicomponent reaction of chalcones, thiosemicarbazide, and 3-(2-bromoacetyl) coumarins in the presence of aqueous sodium hydroxide in refluxing ethanol is reported. The structures of newly prepared compounds have been confirmed by their analytical and spectral (IR, ¹HNMR, ¹³CNMR and mass) data.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Synthesis of 6-(5-sulfanyl-1H-tetrazol-1-yl)-2H-chromen-2-one and 5-methyl-1-(2-oxo-2H-chromen-6-yl)-1H-1,2,3-triazole-4-carboxylic acid

Russian Journal of Organic Chemistry -     

Interaction of 3-acetoacetyl-2H-chromen-2-one with azanucleophilic reagents

The reactions of 3-acetoacetylchromen-2-one with mono- and binucleophilic reagents, under the action of microwave irradiation have been studied. It was shown that depending on the nucleophilicity of the reactant new heterocyclic systems were formed involving the oxo group of the substituent in position 3 of the heterofragment, its opening, or recyclization.     

Alkali metal 2-(1-adamantyl)ethynethiolates: Synthesis and reactions with electrophilic reagents

Treatment of ethyl 2-[1-(1-admantyl)ethylidene]hydrazine-1-carboxylate with thionyl chloride gave 4-(1-adamantyl)-1,2,3-thiadiazole which readily underwent decomposition by the action of strong bases with formation of alkali metal 2-(1-adamantyl)ethynethiolates. The latter were brought into reactions with proton donors and benzyl halides.     

Reactions of (pyrrol-1-yl)furazans with electrophilic reagents

The behavior of (pyrrol-1-yl)furazans in electrophilic substitution reactions (halogenation, nitration, and acylation) was studied. The presence of the furazan ring substantially did not affect the regioselectivity of the reactions but it prevented replacement of all the hydrogen atoms in the pyrrole ring by electrophiles. Dedicated to Academician V. A. Tartakovsky on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1516–1520, August, 2007.     

Synthesis,Crystal Structure and DNA Interaction Study of 3-(2-(3,5-Diphenyl-4,5-dihydropyrazol1-yl)thiazol-4-yl)-2H-chromen-2-one

A new compound 3-(2-(3,5-diphenyl-4,5-dihydropyrazol-1-yl)thiazol-4-yl)-2Hchromen-2-one was synthesized by cyclocondensation of 3,5-diphenyl-4,5-dihydropyrazole-1-carbothioamide with 3-(2-bromoacetyl)-2H-chromen-2-one in ethanol at reflux for 2hrs. The compound was characterized by IR, 1H-NMR, 13C-NMR and single-crystal X-ray diffraction analysis. The newly synthesized compound(C27H19N3O2S) crystallizes in the triclinic system, space group P1 with a = 5.2476(6), b = 18.289(2), c = 23.115(3) , α = 93.546(7), β = 94.715(6), γ = 92.347(7)°, V = 2204.3(4)3, Z = 4, Mr = 449.51, crystal size = 0.38 mm × 0.22 mm × 0.16 mm,(I 2σ(I)) = 35317, 9736, 3785, Rint = 0.081,(Δρ)max = 0.19 and(Δρ)min = –0.24 e·-3. DNA interaction studies revealed that the target compound strongly interacts with DNA through an intercalation binding mode and the binding constant of the compound is 7.45 × 104 M-1.     

Racemic and asymmetric Diels-Alder reactions of 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes

Achiral and chiral 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes were prepared from readily available starting materials. Although more stable than the parent 1-amino-3-siloxy dienes, the 1-(2-oxazolidinon-3-yl)-3-siloxy-1,3-butadienes are still very reactive in Diels-Alder reactions, somewhat more than 1,3-dialkoxy-1, 3-butadienes (e.g., Danishefsky's diene). The cycloadditions of the achiral and chiral dienes with several different dienophiles were examined. The reactions proceeded in good yield, with modest to high endo selectivity. The chiral dienes exhibited excellent facial selectivity in cycloadditions with alpha-substituted acroleins, maleic anhydride and N-phenylmaleimide. Upon reduction and hydrolysis of the cycloadducts, substituted cyclohexenones were obtained with ee's ranging from 22% to >98%.     

Domino reactions between 3-(6-methylchromonyl)acrylonitrile and nucleophilic reagents

The chemical reactivity of electron deficient chromone–linked acrylonitrile [3-(6-methylchromonyl)acrylonitrile (1)] was studied towards some active methylene nitriles and active methylene ketones. Reaction of compound 1 with malononitrile, cyanoacetamide, ethyl cyanoacetate, malononitrile dimer and acetoacetanilide afforded 5-cyanomethylchromeno[4,3-b]pyridines 2–4 and 9. Compound 1 reacted with 1H-benzimidazol-2-ylacetonitrile producing pyrido[1,2-a]benzimidazole derivative 5. Benzonitrile derivatives 6–8 were efficiently synthesized from the reaction of compound 1 with acetylacetone, ethyl acetoacetate and diethylmalonate. In these reactions a diversity of products has been synthesized through a domino process, including Michael addition, retro-Michael with γ-pyrone ring opening followed by different types of recyclization (RORC). Structures of the new synthesized products were deduced on the basis of their analytical and spectral data, and the reaction mechanisms are discussed.     

Synthesis of 3-[4-(1-Benzofuran-2-yl)-1,3-thiazol-2-yl]-2-(4-aryl)-1,3-thiazolidin-4-one Derivatives as Biological Agents

A protocol for the synthesis of 3-[4-(1-benzofuran-2-yl)-1,3-thiazol-2-yl]-2-(4-aryl)-1,3-thiazolidin-4-one derivatives (5a–e) has been developed from 1-(1-benzofuran-2-yl)-2-bromoethanone (2),which served as a key intermediate for the synthesis of the title compounds. The reaction of compound 2 with thiourea furnished 4-(1-benzofuran-2-yl)-1,3-thiazol-2-amine 3, which upon further reaction with various aromatic aldehydes, gave Schiff bases 4a–e. These Schiff bases, when treated with thioacetic acid in the presence of catalytic amount of anhydrous ZnCl₂, yielded thiazolidinone derivatives 5a–e. All the newly synthesized compounds have been characterized by analytical and spectral data and screened for their antimicrobial and analgesic activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Short Synthesis of 1-(3-tert-Butyl-1-phenyl-1H-pyrazol-5-yl)-3-(5-(2-morpholinoethoxy)-2H-chromen-8-yl) Urea Derivatives

A short and efficient synthesis of 1-(3-tert-butyl-1-phenyl-1H-pyrazol-5-yl)-3-(5-(2-morpholinoethoxy)-2H-chromen-8-yl) urea derivatives (1a–c), a novel type of p38 MAPK inhibitors, is described. The Claisen thermal rearrangement of arylpropargyl ethers was employd as a key step to synthesize the chromene core. The solvent effect on the ratio of the resultant two isomers of Claisen thermal rearrangement, namely 2-methylbenzofuran and 2H-chromen, was also investigated.     

5-Substituted-3-(substituted)phenyl-1,3,4-oxadiazolin-2(3H)-ones. Synthesis and reactions with nucleophilic reagents

A new synthesis of 4,4-dialkyl-2-(substituted)phenylsemicarbazides has been developed. The procedure begins with a 5-substituted-3-(substituted)phenyl-1,3,4-oxadiazolin-2(3H)-one, 3 , which is treated with dialkylamine to give a 1-acyl-4,4-dialkyl-2-(substituted)phenylsemicarbazide, 7 . Subsequent base-catalyzed hydrolysis of 7 gives 4,4-dialkyl-2-(substituted)phenylsemicarbazides, 14 , in high yield. With a variety of nucleophilic reagents, the compounds 3 also undergo ring opening.     

(2Z)-3-(5-Hydroxy-4-oxo-4H-chromen-3-yl)acrylonitrile

The title compound, C₁₂H₇NO₃, consists of a chromone moiety substituted in position 3 with an acrylonitrile group in a Z configuration. The two planar groups are twisted with respect to one another. The only significant hydrogen bond in the structure is an intra­molecular O—H·O bond. π–π contacts connecting aromatic groups and C—H·O inter­molecular weak inter­actions lead to a supramolecular layer arrangement.     

Structure,tautomerism, and features of 1-(5-acetyl-2,4-dihydroxyphenyl)-3-(furan-2-yl)prop-2-en-1-one (FC) and 1,1′-(4,6-dihydroxybenzene-1,3-diyl)bis[3-(furan-2-yl)prop-2-en-1-one] (FDC)

Quantum chemistry studies of various tautomeric/rotameric forms of the furanyl analogues of acetyl dihydroxychalcone (FC) and dihydroxydichalcone (FDC) have shown that the thermodynamically most stable molecules are planar. In the crystalline solid phase, both molecules are more (FDC) or less (FC) non-planar. Two relatively strong intramolecular H-bonds, whose existence is evidenced by X-ray, computational, and spectral investigations, stabilize the planar geometry and influence the features of the lowest energy tautomers/rotamers of both compounds. Extending to the visible region, the electronic absorption of FC and FDC is accompanied by an intramolecular electron density shift, a property that could have analytical implications.     

Synthesis and characterization of novel 2-(1-benzyl-3-[4-fluorophenyl]-1H-pyrazol-4-yl)-7-fluoro-4H-chromen-4-one derivatives

Novel 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-4-carbaldehydes 3a to 3e were synthesized via Vilsmeier-Haack reaction of the appropriate 1-benzyl-2-(1-(4-fluorophenyl)ethylidene)hydrazines, derived from 4-fluoroacetophenone 1 with substituted 2-benzylhydrazines 2a to 2e . The base catalyzed condensation of 1-benzyl-3-(4-fluorophenyl)-1H-pyrazole-4-carbaldehydes 3a to 3e with 1-(4-fluoro-2-hydroxyphenyl)ethanone 4 gave (E)-3-(1-benzyl-3-(4-fluorophenyl)-1H-pyrazol-4-yl)-1-(4-fluoro-2-hydroxyphenyl)prop-2-en-1-ones 5a to 5e . On cyclization with dimethyl sulfoxide (DMSO)/I₂, compounds 5a to 5e gave 2-(1-benzyl-3-(4-fluorophenyl)-1H-pyrazol-4-yl)-7-fluoro-4H-chromen-4-ones 6a to 6e . Structures of all novel compounds were confirmed by infrared (IR), proton nuclear magnetic resonance (¹H NMR), carbon nuclear magnetic resonance (¹³C NMR), and mass spectral data. All the synthesized compounds were screened for their antibacterial activities.     

Antioxidant activity of some N-heterocycles derived from 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene) hydrazinecarbothioamide

Efficient and convenient synthesis of coumarin derivatives was accomplished via reactions of 2-(1-(2-oxo-2H-chromen-3-yl)ethylidene)hydrazinecarbothioamide with some carbon electrophiles, e.g. maleic anhydride, dimethyl acetylenedicarboxylate, 1,2-dichloroethane, 3′-nitro-w-bromoacetophenone, N-(4-acetylphenyl)-2-chloroacetamide, ethyl cyanoacetate/3-chlorobenzaldehyde and acetylacetone to construct some N-heterocycles such as thiazolidine, thiazole, pyrimidine and pyrazolone derivatives. The structures of all synthesized products were substantiated from their analytical and spectral data. The antioxidant activities of the synthesized compounds were examined.     

Reactions of tert-butyl N,N-diethyl-N′-(4-phenylthiazol-2-yl)-phosphorodiamidite with electrophilic reagents

Previously unknown amidophosphorous acid derivatives were prepared by transamidation of tert-butyl N,N-diethyl-N′-(4-phenylthiazolyl)phosphorodiamidite with 2-amino-4-phenylthiazole, and their reactions with acetyl and benzoyl chloride were studied. These reactions are shown to proceed regioselectively according to the Arbuzov scheme to give the corresponding ketophosphonates. The reaction of the phosphorodiamidite with acetyl chloride in a 1:2 molar ratio involves formation of acetophosphonate that reacts in the enol form to give the corresponding (1-acetoxy)vinylphosphonate.