Novel Synthesis of Thieno[2,3-c]Pyridazine and Pyrimido[4',5':4,5]thieno[2,3-c]pyridazine Derivatives

Abstract

Novel series of thieno[2,3-c]pyridazines and pyrimido[4′,5′:4,5] thieno-[2,3-c]pyridazines have been synthesized from the readily accessible 4-cyano-5,6-dimethylpyridazin-3(2H)-thione 3b.     

Facile synthetic route to benzo[c]chromenones and thieno[2,3-c]chromenones

Convenient two-step procedure for the synthesis of fused chromenone derivatives was developed. Reduction of the obtained in the Meerwein arylation reaction aryl- and thienylquinones allowed to construct 6H-benzo[c]chromene-6-ones and 4H-thieno[2,3-c]chromen-4-one in a more cost- and time-effective manner in comparison with already known methods. The obtained products have provided a new entry to chromenone derivatives.     

Efficient Synthesis of 3,5,6,7-Tetrahydro-4H-cyclopenta[4,5] thieno[2,3-d]Pyrimidin-4-ones

The title compounds 3,5,6,7-tetrahydro-4H-cyclopenta[4,5]thieno[2,3-d]pyrimidin-4-ones（6） were synthesized by base catalytic reactions of secondary amines with carbodiimides 4, which were obtained from the aza-Wittig reaction of iminophosphoranes（3） with aromatic isocyanates.     

Synthesis and mesomorphic properties of 7-alkoxybezopyrano[2,3-c]pyrazol-3-one

A new series of fused polyheterocyclic aromatic compounds, 7-alkoxybezopyrano[2,3-c]pyrazol-3-one (C- n BPP), were synthesised and characterised by infrared, ¹H-nuclear magnetic resonance (NMR), ¹³C-NMR and two-dimensional ¹H-¹³C cosy spectra. Their phase transition behaviour was investigated by differential scanning calorimetry and polarising optical microscopy. All of these compounds showed enantiotropic mesophases with temperature domains of 12–60°C and 22–69°C on heating and cooling processes for a carbon number of the alkoxy chain from 2 to 10. The effect of the length of the alkoxy chain on the mesomorphic properties was discussed. Comparison of C- n BPP and several kinds of coumarin derivatives indicated that the intermolecular hydrogen bonding acted as the driving force of the mesophase formation.     

Studies on triacetic acid lactone-annulated heterocycles: synthesis of 3-aryloxyacetyl-6-methyl-2,3-dihydrothieno[3,2-c]pyran-4-ones by tandem cyclization

The hitherto unreported 3-aryloxyacetyl-6-methyl-2,3-dihydrothieno[3,2-c]pyran-4-ones were synthesized in 62–71% yield by the sulfoxide rearrangement of 4-(4′-aryloxybut-2′-ynylthio)-6-methyl-2-pyrone. The substrates were synthesized by phase-transfer-catalysed alkylation of the hitherto unreported 4-mercapto-6-methylpyran-2-one.     

Utility of ethyl 5-aminothieno[2,3-c]pyridazine-6-carboxylate in heterocyclic synthesis

The synthesis and application of ethyl 5-aminothieno[2,3-c]pyridazine-6-carboxylates as building blocks for the synthesis of polyfunctionalized heterocyclic compounds are reviewed.     

The photochemical synthesis of 6-acyl-5H-benzo[a]phenoxazin-5-ones

6-Acyl-5H-benzo[a]phenoxazin-5-ones were prepared by the photochemical reaction of 5H-benzo[a]phenoxazin-5-one with aldehydes.

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Die photochemische Synthese von 6-Acyl-5H-benzo[a]phenoxazin-5-one (Kurze Mitteilung)

Zusammenfassung Die Titelverbindungen wurden mittels photochemischer Reaktion von 5H-Benzo[a]phenoxazin-5-onen mit Aldehyden hergestellt.

     

选择性合成双[噻吩并[2,3-d]嘧啶-4(3H)-酮]

以2-氨基-4-三氟甲基-5-甲基-噻吩-3-羧酸乙酯(1)为起始原料制得膦亚胺2.在碳酸钾的催化下,膦亚胺2与芳基异氰酸酯和伯二胺的氮杂Wittig反应制得嘧啶环上2,2’取代的双[噻吩并[2,3-d]嘧啶-4(3H)-酮]3;膦亚胺2与烷基异氰酸酯和伯二胺的氮杂Wittig反应制得嘧啶环上3,3’取代的双[噻吩并[2,3-d]嘧啶-4(3H)-酮]4.化合物3的核磁共振氢谱表明关环反应在嘧啶环的2,2’位;化合物4的核磁共振氢谱表明关环反应在嘧啶环的3,3’位.对合成反应机理的推导及目标产物核磁共振氢谱数据的分析解释了此合成反应的选择性.     

Theophylline as a new and green catalyst for the one-pot synthesis of spiro[benzo[a]pyrano[2,3-c]phenazine] and benzo[a]pyrano[2,3-c]phenazine derivatives under solvent-free conditions

A green, convenient, high yielding and one-pot procedure for the synthesis of novel spiro[benzo[a]pyrano[2,3-c]phenazine] derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-1,4-dione, benzene-1,2-diamines, ninhydrine, and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione (theophylline) as an expedient, eco-friendly and reusable solid base catalyst under thermal, microwave irradiation and solvent-free conditions. This procedure has also been applied successfully for the synthesis of benzo[a]pyrano[2,3-c]phenazines.     

Microwave-Assisted Synthesis and Antifungal Activities of Polysubstituted Furo[3,2-c]chromen-4-ones and 7,8,9,10-Tetrahydro-6H-benzofuro[3,2-c]chromen-6-ones

An efficient and novel microwave-assisted synthesis of furo[3,2-c]chromen-4-ones and 7,8,9,10-tetrahydro-6H-benzofuro[3,2-c]chromen-6-ones via 4-hydroxycoumarins with α-chloroketones or α-bromocyclohexanone in the presence of acetic acid (AcOH)/ammonium acetate (NH₄OAc) using DMF as solvent under microwave irradiation is described. Systematically, antifungal biological tests showed that most of the compounds exhibited potent antifungal activity against Botrytis cinerea, Collecterichum capsica, Alternaria solani, Gibberella zeae, and Rhizoctorzia solani at the concentration of 50 µg/mL. The corresponding EC50 values of these analogues have been detected, and compound 4i showed better antifungal activity against tested fungi Botrytis cinerea and Collecterichum capsica than the reference Osthol.     

An efficient synthesis of novel benzo[b]pyrido[3',2':4,5] thieno[2,3-e][1,6]naphthy-ridine-8-ones

An efficient method for the synthesis of novel benzo[b]pyrido[3',2':4,5] thieno[2,3-e][1,6] naphthyridine-8-one derivatives has been developed using a Pictet-Spengler reaction between 4-(3-aminothieno[2,3-b]pyridin-2-yl)quinoline-2-ones, which could be obtained from the alkylation of 4-bromomethylquinoline-2-ones with 3-cyanopyridine-2-thione followed by a Thorpe-Ziegler isomerization, and aromatic aldehydes under p-TsOH as catalysis in good yields.     

由N-苯基[1,3]苯并噁嗪正离子与烯烃[4+2]反应合成喹啉并[1,2-c][1,3]苯并噁嗪-6-酮衍生物

以BF3·OEt2 为催化剂, 在室温下通过4-羟基-N-苯基[1,3]苯并噁嗪-2-酮的脱羟基产生N-苯基[1,3]苯并噁嗪正离子, 然后与富电子烯烃发生Diels-Alder反应, 合成出了一系列喹啉并[1,2-c][1,3]苯并噁嗪-6-酮和喹啉并[1,2-c][1,3]萘并噁嗪-6-酮衍生物.     

Synthesis of novel benzo[b]pyrimido[4',5':5,4]thieno[2,3-e][1,6]naphthyridine-8-ones via Pictet–Spengler cyclization

An efficient method for the synthesis of novel benzo[b]pyrimido[4',5':5,4]thieno[2,3e]-[1,6]naphthyridine-8-one derivatives via Pictet–Spengler cyclization is reported. The reaction of 4-(3-aminopyrimido[4,5-d]thieno-2-yl)quinoline-2-ones, which could be obtained from Thorpe–Ziegler isomerization of 4-bromomethylquinoline-2-ones and 5-cyano-1,6-dihydro-4-methyl-2-phenyl-6-thioxopyrimidine,with aromatic aldehydes in the presence of BF_3·OEt_2 gives pyrimidothieno[1,6]naphthyridines in good yields.     

Efficient Synthesis of 3,5,6,8-Tetrahydro-4H-thiopyrano[4',3':4,5]thieno[2,3-d]pyrimidin-4-ones via an Iminophosphorane

3,5,6,8-Tetrahydro-4H-thiopyrano[4',3':4,51thieno[2,3-d]pyrimidin-4-ones(7) were synthesized via the base catalytic reactions of amines or phenols with carbodiimides(5),which were obtained from the aza-Wittig reactions of iminophosphoranes(4) with aromatic isocyanates.     

A NOVEL SYNTHESIS OF 2-SUBSTITUTED-4H-THIENO [2,3-d][1,3] OXAZIN-4-ONE AND 2,3-DISUBSTITUTED THIENO [2,3-d]PYRIMIDIN-4(3H)-ONE DERIVATIVES

Abstract

The synthesis of acetic 2-{[1-methyl-2-(4-oxo-5,6,7,8-tetrahydro-4H-benzo [4,5]-thieno [2,3-d] [1,3-oxazin-2-yl)ethylidene]amino}-4,5,6,7-tetrahydrohenzo[b]thiophene ?3-carboxylic acid anhydride 5 and 2-(oxopropyl)-5,6,7,8-tetrahydro-4H-benzo-[4,5] thieno[2,3-d][1,3]oxazin-4-one 7, has been achieved in three steps from ethyl 2-amino-4,5,6,7-tetrahydrobenzo(b]thiophene-3-carboxlate 1 via the reaction with ethyl acetoacetate followed by hydrolysis and acetic anhydride-induced cyclization. The 2-substituent in compound 5 has two functional groups i.e. active methylene and acid anhydride which are suitably located for intramolecular transformation. Thermal and/or base catalyzed intramolecular cyclization of 5 afforded 2-(4-acetoxy-(hydroxyl)-2-methyl-5,6,7,8-tetrahydrobenzo[4,5] thieno[2,3-b]pyridin-3-yl)-5,6,7,8- tetrahydro-4H-benzo[4,5]thieno[2,3-d] [1,3]oxazin-4-one 10 and 9 respectively. Treatment of 5 with hydrazine hydrate, aromatic and/or heterocyclic amines induced the same intramolecular cyclization with a concomitant oxazine-pyrimidine interconversion to give 3-amino(aryl or heteryl)-2-(4-hydroxy-5,6,7,8-tetrdhydrobenzo-[4,5]thieno[2,3-b]pyridin-3-yl)-3,4,5,6,7,8-hexahydrobenzo[4,5] thieno[2,3-d] pyrimid in-4-one 11–14 respectively.     

A concise synthesis of functionalized 2,3-dihydrofuro[3,2-b], [3,2-c], and [2,3-b]pyridines

A strategy for the efficient and rapid one-pot synthesis of 2-aryl-2,3-dihydrofuro[3,2-b], [3,2-c], and [2,3-b]pyridines from readily available o-nitropicolines and aromatic aldehydes is described. The key transformation involves reaction of o-nitropicolines with aromatic aldehydes in the presence of TBAF and Hünig's base giving rise to functionalized products having molecular complexity suitable for further manipulation.     

Polyethylene glycol-promoted synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives in water

Synthesis of pyrimido[1,2-a]benzimidazole and pyrano[2,3-c]pyrazole derivatives were achieved using polyethylene glycol (PEG-400) as promoting reaction medium in water under catalyst-free conditions at reflux and room temperature, respectively. The structure of pyrimido[1,2-a]benzimidazole was confirmed using ¹H NMR, ¹³C NMR, DEPT, and HMBC experiments. The promising points for the present methodology are efficiency, generality, high yield, short reaction time, cleaner reaction profile, ease of product isolation, simplicity, potential of recycling reaction medium, and finally agreement with green chemistry protocols.     

Synthesis and Reactions of Some New Thieno[2,3-C]pyridazine Derivatives

The alkylation of 4-cyano-5,6-dimethylpyridazin-3(2H)-thione 3 with some halo compounds gave the S-alkylated products 4a–c , which upon treatment with ethanolic sodium ethoxide afforded the cyclized thienopyridazines 5a–c as products. Pyridazothienotriazines 6a–c were prepared by the treatment of compounds 5a–c with nitrous acid, while their reaction with triethyl orthoformate and with carbon disulfide gave the corresponding pyrimidothienopyridazines 7a–c , and 8a–c , respectively. S-alkylated products 9a–o were obtained by the reaction of 8a–c with some halo compounds.