Thioureidoquinazolin-4(3H)-ones

3-(N′, N′-Dialkylthioureido)quinazolin-4(3H)-ones prepared by the reaction of 3-aminoquinazolin-4(3H)-one with thiuram disulfides undergo the previously, unknown acid-induced recyclization to give the corresponding 5-(2-aminophenyl)-2-dialkylamino-1,3,4-thiadiazoles. The structures of the products obtained were confirmed by IR and¹H and¹³C NMR data. A plausible mechanism of the recyclization is discussed.     

Synthesis of 3-S-hetaryl-substituted pyridin-2(1H)-ones and 5,6-dihydropyridin-2(1H)-ones*

A method has been developed for the synthesis of 3-S-hetaryl-substituted pyridin-2(1H)-ones and 5,6-dihydropyridin-2(1H)-ones based on the base catalyzed cyclization of N-(3-oxoalkyl)- and N-(3-oxoalkenyl)amides which contain a divalent sulfur atom in an α-position to a carbamoyl group and bound to the heterocycle.     

Synthesis of (hetero)arylated pyridazin-3(2H)-ones via Negishi reaction involving zincated pyridazin-3(2H)-ones

Zincated pyridazin-3(2H)-ones generated via bromine-magnesium exchange followed by transmetalation using ZnCl(2) or via lactam-directed ortho C4-H zincation with TMPZnCl·LiCl have been synthesized. These in situ created organometallics can be used in Negishi reactions with iodo(hetero)arenes delivering a new approach toward (hetero)arylpyridazin-3(2H)-ones.     

Photochemistry of Thiophen-2(5H)-ones

Mechanistic evidence for the light-induced ring opening of thiophen-2(5H)-ones 1 in alcohols affording α, β-unsaturated mercapto esters 2 is presented. Regio-and stereochemical aspects of the ring closure of alkenylthio (type 3 ) radicals 15 and 17 to S-heterocycles 16 and 18 , of 3-thiahex-5-enyl radicals 4 to (tetrahydrothien-3-yl)methyl radicals 6 and of (2,3-dihydrothien-3-yl)methyl radicals 30 (type 7, but-3-enyl radicals) to cyclopropane-methyl radicals 29 are discussed. Irradiation (λ 350 nm) of 1 in cyclohexane in the presence of 2,3-dimethylbut-2-ene affords [2 + 2] cycloadducts 14 albeit in very low yields.     

微波辐射促进选择性合成4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮和嘧啶-2(1H)-酮

探讨了在微波加热条件下,芳香醛、取代苯乙酮和尿素的三组分反应在N,N-二甲基甲酰胺(DMF)中制得4,6-二芳基-3,4-二氢嘧啶-2(1H)-酮类化合物,收率为68%～84%.若在反应体系中加入三甲基氯硅烷,该三组分反应则高产率(66%～87%)地生成相应的脱氢产物4,6-二芳基嘧啶-2(1H)-酮类化合物.该反应具有反应条件温和、产物收率高、操作方便等优点,为4,6-二芳基-嘧啶-2(1H)-酮类药物中间体的合成提供了一条全新的路线.     

5,6-Dihydropyridin-2(1H)-ones and 5,6-dihydropyridine-2(1H)-thiones (review)

Data on methods for the production of 5,6-dihydropyridin-2(1H)-ones and 5,6-dihydropyridine-2(H)-thiones and their biological activity are reviewed.Omsk State University, Omsk, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 147–167, February, 1999.     

Azo coupling of 5-substituted furan-2(3H)-ones and 1H-pyrrol-2(3H)-ones with arene(hetarene)diazonium salts

5-Substituted furan-2(3H)-ones and 1-phenyl-1H-pyrrol-2(3H)-ones reacted with diazonium salts derived from substituted anilines and 1H-1,2,4-triazol-5-amine to give azo coupling products at the methylene group in the heteroring. The products were found to exist as hydrazone tautomers.     

Heterocyclic studies—XXIV: Mass spectra of some pteridin-4(3H)-ones and 3-methoxypteridin-4(3H)-ones

Mass spectra of pteridin-4(3H)-one and all its mono-, di- and tri-C-methyl derivatives are recorded. Spectra of 3-methoxypteridin-4(3H)-one and four of its mono- and dimethyl derivatives are also recorded. Pteridin-4(3H)-one fragments mainly by loss of CO and HCN in either order. Methyl substitution in the pyrazine ring leads to that ring fragmenting in preference to the oxygen bearing pyrimidine ring. Elucidation of fragmentation pathways was facilitated by changes in peak positions with changing methyl substitution patterns. 3-Methoxypteridin-4(3H)-ones fragment mainly through initial loss of CH₂O, but the ions so produced break down differently from isomeric molecular ions of pteridin-4(3H)-ones. Several fragmentation pathways are discussed.     

Synthetic methods for spirofuran-2(5H)-ones (microreview)

Chemistry of Heterocyclic Compounds - This microreview focuses on the preparation of spirofuran-2(5H)-ones, including ipso substitution strategy, PPh3-catalyzed reactions, ring opening reactions,...     

Synthesis of 5,6-dimethoxyquinazolin-2(1H)-ones

Synthesis of 5,6-dimethoxyquinazolin-2(1H)-one derivatives was the subject of investigations leading to the preparation of title compounds 11, 13, 14 and 26 . Target quinazolines 1 were synthesized in three ways; the route starting from o-vanillin via the intermediacy of 6-amino-2,3-dimethoxyacetophenone ( 19 ) was used for most of the preparative work. The unexpected formation of an acid-labile dimer of 13 was discovered and solid state ¹³C nmr was used for structural assignment. The 5-methoxy substituent in these systems shows anomalous spectral characteristics and, in one case, was cleaved in acid media to 22 .     

Synthesis of 2,3-Dihydroquinazoline-4(1H)-ones

An efficient, inexpensive, and heterogeneous catalyst, [Al(H₂PO₄)₃], was applied in a three-component, one-pot cyclocondensation reaction of isatoic anhydride with primary amines (or ammonium salts) and aldehydes to afford the corresponding quinazolinone derivatives in excellent yields. Reactions occurred under thermal solvent-free conditions. It was found that this solid acidic catalyst could be easily recovered and reused for at least three cycles without any loss of activity.     

The synthesis of isoindolin-3-ones,Phthalazin-4(3H)-ones and related systems

The reaction between methyl 2-cyanobenzoate and its pyridine analogues gave isoindolin-3-ones, phthalazin-4(3H)-ones and their corresponding aza analogues. Some reactions of 1-benzylaminoiminoisoindolin-3-one 5b were investigated.     

Solid-phase syntheses of 6-arylpyridazin-3(2H)-ones

The 3-chloropyridazine moiety was immobilized on a Wang resin, using two different methodologies. The first of these involved direct nucleophilic substitution of 3,6-dichloropyridazine with the alcoholate of Wang resin. The experimental conditions were optimized. The second method involved a Mitsunobu reaction between the Wang resin and 6-chloropyridazin-3-ol during which a problem of regioselectivity was observed. The so-obtained chloropyridazine-containing resins were subsequently reacted with various arylboronic acids under Suzuki conditions. Acid cleavage yielded 6-arylpyridazin-3(2H)-ones with high chemical purity.     

Green chemistry approach to the synthesis of 3-substituted-quinazolin-4(3H)-ones and 2-methyl-3-substituted-quinazolin-4(3H)-ones and biological evaluation

ABSTRACT

A synthesis of two series of 3-substituted quinazolinones was performed utilizing a green chemistry approach, deep eutectic solvents and microwaves, namely. 2-Methyl-3-substituted-quinazolin-4(3H)-one derivatives were synthesized in a two-step reaction, using choline chloride:urea deep eutectic solvent (DES). 3-Substituted-quinazolin-4(3H)-ones were synthesized in one-pot one-step reaction of anthranilic acid, amines and orthoester in a microwave reactor. For the synthesis of 2-methyl-3-substituted-quinazolin-4(3H)-ones, first conventional synthesis of benzoxazinone, as an intermediate, was performed. Further, benzoxazinone in reaction with corresponding amines, in choline choline:urea deep eutectic solvent, furnished desired compounds. These procedures are based on green principles with the aim of developing synthetic routes for the potential antitumor agents. All compounds were characterized by LC/MS, ¹H NMR and ¹³C NMR spectral techniques. Compound 1 bearing trifluoromethoxyphenyl group showed promising activity against HuT-78 cell line with IC₅₀ of 51.4?±?5.1?µM.     

Convenient Synthesis of 5-Alkylfuran-2(5H)-ones

A convenient synthesis of 5-alkylfuran-2(5H)-ones are described starting from 3-nitropropanoate and aldehydes, promoted by neutral alumina, in 35–60% overall yields, via a condensation–lactonization–elimination pathway.      

Electro-reductive C-H cyanoalkylation of quinoxalin-2(1H)-ones

Herein, we report a practical electro-reductive protocol for the direct C–H cyanoalkylation of quinoxalin-2(1H)-ones via iminyl radical-mediated ring opening. These mild reactions proceed under metal-, reductant-, and reagent-free conditions to provide synthetically useful cyanoalkylated quinoxalin-2(1H)-ones.     

Photochemistry of N-aryl-2(1H)-pyrimidin-2-ones

Irradiation of N-aryl-2(1H)-pyrimidin-2-ones ($\text{3a}$-$\text{c}$) in a mixed benzene-alcohol solution afforded the products initiated by Type I cleavage, 1-(3-alkoxycarbonylamino-2-propene)-N-arylimines ($\text{4a}$-$\text{c}$, $\text{5}$, and $\text{6}$) in 45–51% yields.     

Synthesis of 2-aryl-oxazolo[4,5-c]quinoline-4(5H)-ones and 2-aryl-thiazolo[4,5-c]quinoline-4(5H)-ones

[reaction: see text] Novel and highly efficient syntheses of oxazolo[4,5-c]quinoline-4(5H)-ones (1) and thiazolo[4,5-c]quinoline-4(5H)-ones (2) from ethyl 2-chlorooxazole-4-carboxylate (4) and ethyl 2-bromo-5-chlorothiazole-4-carboxylate (13), respectively, are described.