低价钛促进的1,2-二氢喹唑啉-4(3H)-酮的合成

喹唑啉-4(3H)-酮是一类生物碱,取代喹唑啉-4(3H)-酮具有广泛的药理学活性．因而对其合成方法和合成新型喹唑啉-4(3H)-酮的衍生物的研究已成为热点．低价钛试剂是一种还原偶联试剂,它能引起醛酮的还原偶联生成烯烃,还能引起其它官能团的还原偶联反应,该反应已应用于天然产物和一些碳环化合物的合成,而用于杂环化合物的合成研究报道较少．本文报道低价钛试剂(TiCl4-Zn体系)促进的1,2-二氢喹唑啉-4(3H)-酮的合成。     

Synthesis of novel 8-nitro-substituted 1,3-benzothiazin-4-ones

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Synthesis of 2-Phosphono Alkyl 1,2-Benzisoselenazol-3(2H)-ones

A series of 2-phosphonoalkyl 1,2-benzisoselenazol-3(2H)-ones were designed and synthesized via reaction 2-chloroselenobenzoyl chloride with 1-hydrazinobenzyl phosphonate. The structures of all new compounds were confirmed by spectroscopic methods and microanalyses.     

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 1-substituted 3-nitroquinolin-4(1H)-ones

A versatile synthetic method for preparing 1-substituted 3-nitroquinolin-4(1H)-ones from corresponding 2-fluoro-α-nitroacetophenones is demonstrated by the synthesis of 6,7-difluoro derivatives 7a-c . The method involves sequential treatment of the starting nitroacetophenone with triethyl orthoformate and the appropriate amine, followed by a nucleophilic cyclization reaction under mild conditions. The C-7 fluorine atom of 7 can be displaced by cyclic amines. Substituted 6-fluoro-7-(4-methyl-1-piperazinyl)-3-nitroquinolin-4(1H)-ones 8a-c were prepared in this way.     

Novel syntheses of 2,3-dihydro-1,5-benzothiazepin-4(5h)-ones and 2h-1,4-benzothiazin-3(4h)-ones

Nucleophilic additions of alpha-mercaptoalkanoate esters and beta-mercaptoalkanoate acids to benzoquinone diimines, followed by cyclization with trifluoroacetic acid or 1,3-dicyclohexylcarbodiimide (DCC), provide novel, high-yielding syntheses of 2H-1,4-benzothiazin-3(4H)-ones (3a-f) and 2,3-dihydro-1,5-benzothiazepin-4(5H)-ones (5a-c), respectively.     

Synthesis and antimicrobial activity of some 2-alkyl-2H-1,4-benzothiazin-3(4H)-ones and 2-alkylbenzo[d]imidazolo[2,1-b]-thiazolidin-3-ones

Summary Sodium 2-aminothiophenoxide (1) reacts with ethyl 2-bromoalkanoates (2) under direct cyclization to form 2-alkyl-2H-1,4-benzothiazin-3(4H)-ones (3). Reaction of the sodium salt of 2-mercaptobenzimidazole (4) with2 or 2-bromoalkanoic acids (5) affords only S-alkylated products (6 or7, respectively). The cyclization products — 2-alkylbenzo[d]imidazolo[2,1-b]thiazolidin-3-ones (8) — can be obtained only from the corresponding 2-(2-benzimidazolylthio)alkanoic acids (7) by the action of acetic anhydride. Both compounds3 and8 exhibit only moderate antimicrobial activity against some gram-positive bacteria.

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Synthese und antimikrobielle Wirkung von einigen 2-Alkyl-2H-1,4-benzothiazin-3(4H)-onen und 2-Alkylbenzo[d]imidazolo[2,1-b]thiazolidin-3-onen

Zusammenfassung Bei der Reaktion von Natrium-2-aminothiophenolat mit 2-Bromoalkansäure-ethylestern (2) entstehen als Cyclisierungsprodukte 2-Alkyl-2H-1,4-benzothiazin-3(4H)-one (3). Die Umsetzung von Natriumbenzimidazol-2-thiolat mit2 oder mit 2-Bromoalkansäuren (5) liefert nur S-Alkylierungsprodukte (6 oder7). Die Cyclisierungsprodukte — 2-Alkylbenzo[d]imidazolo[2,1-b]thiazolidin-3-one (8) — sind nur durch Umsetzung von entsprechenden 2-(2-Benzimidazolylthio)-alkansäuren (7) mit Acetanhydrid erhältlich. Die Verbindungen3 und8 weisen nur mäßige antimikrobielle Wirkung gegen einige gram-positive Bakterien aus.

     

Synthesis and antitumor activities of novel bis-quinazolin-4(3H)-ones

With the aim of obtaining new antitumor agents, a series of bis-quinazolin-4(3H)-ones ( 3a-3 f ) were designed and synthesized. These products contain 4-oxo-1,2,3,4-tetrahydro-quinazoline and 3H-quinazolin-4-one moieties linked together via a propyl chain. Cytotoxic activities of 3a-3 f were evaluated against lung adenocarcinoma (A549), breast carcinoma (MCF-7) and ovarian cancer (SKOV3) cell lines using MTT method. Cisplatin was used as a positive control. Among the tested compounds 3a , 3b , and 3e showed the best cytotoxic activities against all cancerous cell lines with IC₅₀ values even less than cisplatin. Compounds 3d and 3f also showed desirable cytotoxic activities especially against A549 and MCF-7.     

3-取代-(1H)-嘧啶[1,2-α]喹啉-1-酮和2-取代嘧啶[1,2a]苯骈咪唑-4-(10H)-酮的简便合成法

丙二酸亚异丙酯及乙烯基硫代缩酮均是重要的有机合成试剂。而新近开发的5-(双甲硫基亚甲基)丙二酸亚异丙酯(1)既具有丙二酸亚异丙酯的环状结构,又具有乙烯基硫代缩酮的结构特征,它是一种多功能新的合成试剂。其最重要的性质是它可与多种亲核试剂发生加成反     

Facile and One-Pot Synthesis of 1,2-Dihydroquinazolin-4(3H)-ones via Tandem Intramolecular Pinner/Dimroth Rearrangement

An efficient synthetic method for the preparation of quinazolin-4-one derivatives was designed. The facile condensation of aromatic o-aminonitriles with aromatic aldehydes catalyzed by Lewis acid give 1,2-dihydroquinazolin-4(3H)-ones in moderate to good yields under refluxing dimethylformamide.     

Synthesis and structure of 2-(nitromethylene)-2H-1,4-benzothiazin-3(4H)-one

A new representative of benzothiazines, (2Z)-2-(nitromethylene)-2H-1,4-benzothiazin-3(4H)-one, was synthesized, and its structure was studied. According to ¹H NMR, IR, and UV spectral and X-ray diffraction data, the molecules are planar highly conjugated structures that exist in crystal as centrosymmetric dimers; the latter form layers overlapping with each other and held together by strong π-π interaction between the carbonyl groups of neighboring layers.     

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.     

Reaction of furan-2(3H)-ones with 1,2-binucleophiles

Reactions of 5-substituted furan-2(3H)-ones with ethylenediamine, 2-aminoethanol, and o-aminophenol do not stop at the stage of formation of the corresponding 4-oxoalkanoic acid amides but lead to new bi-and tricyclic structures as a result of double intramolecular cyclodehydration.     

Syntheses and reactions of 1,2-dihydrocyclobuta[c]isoquinolin-4(3H)-ones

Two-step synthesis of 1,2-dihydrocyclobuta[$\text{c}$]isoquinolin-4(3H)-ones, novel cyclobutane-fused heterocycles, from 3-methoxy-2-methylisoquinolin-1(2H)-one and their reacion with olefins are described.     

Synthesis of 1,2-phenylenedimethanols by base-promoted reduction of isobenzofuran-1(3H)-ones with silane

An efficient method for preparation of substituted 1,2-phenylenedimethanols and aliphatic 1,4-diols that are valuable intermediates in organic synthesis, has been developed by the base-promoted reduction of isobenzofuran-1(3H)-ones and γ-lactones with silane under mild conditions. Compared with traditional procedures using stoichiometric amounts of metal hydrides and alkyl reductants, the present method avoids the use of sensitive reagents and is operationally simple, and a broad variety of functional groups are tolerated.     

Synthesis of 5-phenylpyrrolo[1,2-b][1,2,5]-triazepin-2(3H)-ones

The synthesis of a series of 5-phenylpyrrolo[1,2-b][1,2,5]triazepin-2(3H)-ones 1 as potential anxiolytic agents is described. Benzoylation of 1-phthalimidopyrrole, followed by hydrolysis, gave the 1-amino-2-benzoylpyrroles 3 . These were further functionalized to give the penultimate 1-aminoacetamido-2-benzoylpyrroles 8 and 9 , which were cyclized to the target pyrrolotriazepines 1.     

Synthesis and Antimicrobial Activity of Quinazolin-4(3H)-ones Incorporating Sulfonamido-4-thiazolidinone

Some new derivatives 7‐chloro‐2‐[2‐(2,6‐dichlorophenyl)amino]benzyl‐3‐[4‐(2‐substituted phenyl‐4‐oxo‐ thiazolidin‐3‐yl)phenyl]sulfonamido‐quinazolin‐4(3H)‐ones 5a – 5l were synthesized from 2‐[2‐(2,6‐dichloro‐phenyl)amino]phenyl acetic acid via acid chloride, benzoxazinone, amino quinazolin‐4(3H)‐one and Schiff base formation. The synthesized compounds were screened for in vitro antibacterial and antifungal activities by broth micro dilution method. Some of the Schiff base as well as 4‐thiazolidinone derivatives showed promising antibacterial activity while pronounced antifungal activity was observed against C. albicans.     

Combined experimental and computational study on the energetics of 1,2-benzisothiazol-3(2H)-one and 1,4-benzothiazin-3(2H, 4H)-one

The present work reports an experimental and computational study of the energetics of 1,2-benzisothiazol-3(2H)-one and 1,4-benzothiazin-3(2H, 4H)-one. The standard (p° = 0.1 MPa) massic energy of combustion, at T = 298.15 K, of each compound was measured by rotating bomb combustion calorimetry, in oxygen that allowed the calculation of the respective standard molar enthalpy of formation, in the condensed phase, at T = 298.15 K. The standard molar enthalpies of sublimation, at T = 298.15 K, were measured by high-temperature Calvet microcalorimetry. From the combination of data obtained by both techniques we have calculated the standard molar enthalpies of formation, in the gaseous phase, at T = 298.15 K. In addition, computational calculations were carried using the density functional theory with the B3LYP functional and the 6-31G1 basis set and some correlations between structure and energetics were obtained for the keto and enol forms of both compounds. Using the G3(MP2)//B3LYP composite method and various appropriate reactions, the standard molar enthalpies of formation of 1,2-benzisothiazol-3(2H)-one and 1,4-benzothiazin-3(2H, 4H)-one, at T = 298.15 K, were computationally derived and compared with the experimental data. The aromaticity of 1,2-benzisothiazol-3(2H)-one, 1,4-benzothiazin-3(2H, 4H)-one and that of some related species was evaluated by analysis of nucleus independent chemical shifts (NICS).