Preparation of some 4-hydroxyl-1-methyl-1H-2,1-benzothiazine-3-carboxanilide 2,2-dioxides

An improved, 3-step synthesis of 3,4-dihydro-1-methyl-1H-2,1-benzothiazin-4-one 2,2-dioxide has been developed. This general method offers a more facile entrance into the 2,1-benzothiazine 2,2-dioxide heterocyclic system than was heretofore available. Preparation of several 3-carbox-anilides was accomplished by interaction of this ring system with various isocyanates. The resulting carboxanilides are moderately strong, enolic acids.     

Mass spectra of heterocyclic compounds VI. 3,4-dihydro-1H-2,3-benzothiazine 2,2-dioxides

The mass fragmentation behaviour of 3,4-dihydro-1H-2,3-benzothiazine 2,2-dioxides was studied. The rationalizations suggested are supported by accurate mass measurements, metastable evidence and deuterium labelling.     

Keggin Heteropolyacid Catalyzed Synthesis of Isoxazolo[5,4-d]pyrimidine-4,6(5H,7H)-diones at Room Temperature

Isoxazolo[5,4‐d]pyrimidine‐4,6(5H,7H)diones 2a – 2f have been synthesized from the reaction of ethyl 5‐amino‐3‐methyl‐4‐isoxazole carboxylate ( 1 ) with aryl isocyanates in the presence of Keggin heteropolyacid H₃[PW₁₂O₄₀] as a green solid acid catalyst at room temperature in a one‐pot process in good yields.     

3,4-二氢-1H-2-苯并吡喃衍生物化合成

3,4-二氢-1 H-2-苯并吡喃也俗称异色满(isochroman)。近年来,将该类化合物引入到药物合成中的研兖引起了人们的兴趣。虽然,已经合成出许多具有镇痛、降血压、抗组胺。和抗肿瘤等药理活性的3,4-二氢-1 H-2-苯并吡喃类化物,合但大都为异色满环上的1,3,4位取代衍生物或者螺环化合物,关于并杂环合成方面的研究至今不多见,作者前     

Synthesis of 3,4-Dihydro-5H-1-Thia-3,5,6,8-tetraazaacenaphthylenes

Reaction of ethyl 5-amino-4-(substituted amino) -2-methylthiothieno[2, 3-dlpyrimidne-6-carboarytates with formaldehyde in the presence of hydrochloric acid resulted in the synthesis of the corresponding ethyl 3, 4-dihydro-7-methylthio-5H-1-thia-3, 5, 6, 8-tetraazaacenaphthylene-2-carboxylates, which are examples of anew heterocyclic system.     

Bioglycerol-Based Sulfonic Acid-Functionalized Carbon Catalyst as an Efficient and Reusable Catalyst for One-Pot Synthesis of 3- Substituted-2H-1,4-Benzothiazines

Abstract

A simple and efficient synthetic protocol has been developed for the synthesis of 3-substituted-2H-1,4-benzothiazines by using bioglycerol-based sulfonic acid-functionalized carbon catalyst, devoid of corrosive acidic and basic reagents. The developed method has the advantages of good to excellent yields, short reaction times, operational simplicity, and a recyclable catalyst.     

Facile Synthesis of 4H-1,2,4-Benzothiadiazine-1,1-dioxides

A short and efficient synthesis of the title compound based on racemate resolution is described.     

Convenient Synthesis of 2,2-Dimethyl-3,4-dihydro-2H-pyrano[2,3-b]quinolines

A convenient general synthesis of 2,2-dimethyl-3,4-dihydro-2H-pyrano[2,3-b]quinolines using the Wittig reaction is described. The o-nitrobenzaldehydes (1a–d) on reaction with phosphorane 2 provided ( E )-ethyl-α-(2,2-dimethylprop-2-ene)-2-nitrocinnamates (3a–d) in excellent yields, which on cyclization with polyphosphoric acid followed by reductive cyclization using Fe/HCl afforded dihydropyranoquinolines (5a–d). Alternatively, the pyranoquinolines 5a–d were also synthesised from esters 3a–d by employing domino reductive cyclization in a single step.     

Chemoselective Dehydrogenation of 3-[2-（3,4-Dihydro-1-naphthalenyl）ethyl]imidazolidine-2,4-diones： a New and Convenient Synthesis of 13,16-Diazaequilenin analogs

The synthesis of the title compounds starting with the chemoselective dehydrogenation of 3-[2-(3,4-dihydro-1-naphthalenyl)ethyl]imidazolidine-2,4-diones has been described.     

Chemical Immobilization of Heteropolyacid Catalyst on Inorganic Mesoporous Material for use as an Oxidation Catalyst

Recent progress on the chemical immobilization of heteropolyacid (HPA) catalyst on inorganic mesoporous material is reported in this review. Mesostructured cellular foam silica, mesoporous carbon, and nitrogen-containing mesoporous carbon were used as supporting materials. The mesoporous materials were modified to have a positive charge, and thus, to provide sites for the immobilization of HPA catalyst. By taking advantage of the overall negative charge of heteropolyanion, the HPA catalyst was chemically immobilized on the surface-modified mesoporous material as a charge-compensating component. Characterization results showed that the HPA catalyst was finely and molecularly dispersed on the surface of mesoporous material via strong chemical immobilization, and that the pore structure of mesoporous material was still maintained even after the immobilization of HPA catalyst. The supported HPA catalysts were applied to the model vapor-phase ethanol conversion, 2-propanol conversion, and methacrolein oxidation reactions. The supported HPA catalyst showed a better oxidation catalytic activity than the unsupported HPA catalyst in the model reactions. The enhanced oxidation catalytic performance of the supported HPA catalyst was attributed to the finely dispersed HPA catalyst, which was chemically immobilized on the positive site of mesoporous material by sacrificing its proton (Brönsted acid site). The HPA catalyst chemically immobilized on mesoporous material served as an excellent oxidation catalyst.     

2-Chloro-3-quinolinecarboxaldehyde in the Synthesis of Condensed Quinoline Systems. 1. Synthesis of Derivatives of 3,4-Dihydro-2H-[1,3]thiazino[6,5-b]quinolines

A method for the synthesis of derivatives of previously unknown heterocyclic systems - 3,4-dihydro-2H-[1,3]thiazino[6,5-b]quinolines - has been developed based on 7,8-dimethyl-2-chloro-3-quinolinecarboxaldehyde via the consecutive steps of conversion into its Schiff's base with a primary amine, reduction to the corresponding aminomethyl derivative, conversion to the thiourea with isothiocyanates, and heterocyclization by intramolecular substitution of the chlorine atom.     

硅胶固载杂多酸离子液体催化剂bmim-PW12/SiO2的制备及其在酯化反应中的应用

采用溶胶-凝胶法将杂多酸功能化离子液体bmim-PW12(1)固载到硅胶上制得硅胶固载杂多酸功能化离子液体催化剂bmim-PW12/SiO2[2-x(x=5,15,25,35,50)],采用TG-DTG,FT-IR,N2低温吸附脱附,XRD和正丁胺电位滴定等方法表征2的结构、织构性能和酸性。结果表明,2-x保持了1的Keggin结构,且1被较好地固载在硅胶上;2-x具有大的比表面积和强酸性。用7%的2-35催化乙酸与正丁醇的酯化反应,收率88.5%,且2-35重复使用5次后收率仍可达到75.4%。     

LiBr as an Efficient Catalyst for One-pot Synthesis of Hantzsch 1,4-Dihydropyridines under Mild Conditions

A simple, inexpensive and efficient one‐pot synthesis of 1,4‐dihydropyridines has been accomplished via lithium bromide‐catalyzed Hantzsch three‐component condensation reaction of an aldehyde, α,β‐ketoester and ammonium acetate in acetonitrile at room temperature in good to excellent yields. The present protocol is applicable to wide range of substrates including aliphatic, aromatic and heterocyclic aldehydes affording 1,4‐dihydropyridines.     

Synthesis of 3,4-Dihydro-4-Hydroxy-2,2-Dimethyl-2H-1-Benzopyran-5 8-Dione. A Potential Key Intermediate for the Preparation of Naphtho[2,3-b]Pyranoquinones

The synthesis of pyranoquinone 6 and its application to the elaboration of pyranonaphthoquinone 1b is described.     

1-茚满酮合成方法研究进展

1-茚满酮类化合物是许多药物和天然产物合成中的中间体, 有关这类化合物的合成方法仍然不断得到更新. 按照关环位点对于这些合成方法进行了综述, 着重介绍了2000以来的合成新进展.     

Synthesis of Asymmetric 4H-1, 3, 2-Benzodioxaphosphorin 2-Sulfides from Intramolecular Cyclization Reaction

Avarietyofbiologicalactivitiesofsome4H-l,3,2-benzodioxaphosphorin2-sulfideshavebeenreported,forexampletheinsecticideSalithionl.Thecyclicphosphonothionateshavebeenpreparedbyintermolecularcondensationofphosphorodichloridothioateswithsalicylalcoholoritsderivativesinthepresenceofabase=,andbyintramolecularcyclizationreactionofthesalicylalasthestartingmaterial3.However,theintramolecularcyclizationreactionofthe2-hydrobenzophenonesandstereochemicalstudieshavenotbeenreported.Wenowdescribeanewsynthesis…     

SnCl4-Catalyzed Aza-Acetalization of Aromatic Aldehydes: Synthesis of Aryl Substituted 3,4-Dihydro-2H-1,3-benzoxazines

Stannic tetrachloride was an efficient Lewis acid catalyst for the aza-acetalization of aromatic aldehydes with o-arylaminomethyl phenols, and a series of novel aryl substituted 3,4-dihydro-2H-1,3-benzoxazines were prepared in good yields under mild conditions. SnCl₄ was a more efficient catalyst for the reaction than p-toluenesulfonic acid, sulfuric acid, and aluminium chloride.