1H-吡唑-4-甲酸的合成改进

以氰乙酸乙酯和原甲酸三乙酯为原料,通过Claisen酯缩合、合环、脱氨和水解得到1H-吡唑-4-甲酸.用质谱(MS)、核磁共振氢谱(1HNMR)和核磁共振碳谱(13C NMR)表征了化合物的结构.实验结果表明,1H-吡唑-4-甲酸的收率由文献报道的70%提高到了97.1%.     

Synthesis of new pyrido[2,3-d]pyrimidine derivatives by three-component condensation of 5-acetyl-4-aminopyrimidines, cyclohexane-1,3-diones, and orthocarboxylic acid esters

A three-component condensation of 5-acetyl-4-aminopyrimidine derivatives with dimedone (or cyclohexane-1,3-dione) and triethyl orthoacetate (or triethyl orthopropionate) gave derivatives of 7-(1,3-dioxocyclohex-2-ylidene)-7,8-dihydropyrido[2,3-d]pyrimidine. These heterocyclic compounds containing the enamino ketone fragment can form boron chelates under the action of butoxy(diphenyl)borane. Dedicated to Academician O. M. Nefedov on the occasion of his 75th birthday. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2006–2011, November, 2006.     

Synthesis of 1-Substituted 4(1H)-Quinazolinones Under Solvent-Free Conditions

Abstract

Heating a mixture of 2-(N-alkylamino)benzoic acids, triethyl orthoformate, and ammonium acetate under solvent-free conditions generated 1-substituted 4(1H)-quinazolinones in 73?99% yields. Moreover, a possible reaction pathway was proposed.     

Synthese Originale de 5-Aryl (ou 5-benzyl)-2[(1-Diethoxyphosphonyl)methyl]-1,3,4-oxadiazoles par Action du Phosphonomethylhydrazide sur les Imidates N-Acyles

The phosphonomethylhydrazide 2a reacts with N-acylated imidates 3a–d to give the corresponding 5-aryl (or 5-benzyl)-2-[(1-diethoxyphosphonyl)methyl]-1,3,4-oxadiazoles 4a–d after the elimination of ethanamide 5. Compounds 2a–e are prepared by the action of triethyl phosphonoacetate 1 with hydrazine and its derivatives. The structures of 1,3,4-oxadiazoles 4a–d and hydrazides 2a–e have been unequivocally confirmed by means of IR, ¹ H, ¹³ C, ³¹ P NMR and mass spectrometry.     

Oxalic Acid Catalyzed Three Component One Pot Synthesis of 3,4‐Dihydroquinazolin‐4‐ones

An efficient one-pot method for synthesis of an array of 3,4-dihydroquinazolin-4-ones from anthranilicacid, triethyl orthoformate, and anilines using oxalic acid as a catalyst was described. The present protocol offers improvements for the synthesis of 3,4-dihydroquinazolin-4-ones with regard to short reaction time, high yields of products, and simplicity in operation.     

Regioselectivity in the C-alkylation of triethyl 3-methyl-4-phosphonobut-2-enoate

The reaction of triethyl 3-methyl-4-phosphonobut-2-enoate (1) with three alkyl halides AlkX (Alk=Prⁱ, Me₂CHCH₂CH₂, andc-C₅H₉; X=Br, I) in the system KOH(solid)∩DMF∩Buⁿ ₄NBr at ≈20°C gives exclusively products of alkylation at C(2) with Δ² and/or Δ³ position of the double bond. Under the same conditions, the reaction of 1 with MeI gives a mixture of products with different substitution patterns. Only the use of an ion pair extraction technique affords 2-methyl-Δ²-products selectively, albeit in rather moderate yields. The Horner—Emmons olefination of PhCHO with the resulting phosphonates gives ethyl 2-alkyl-3-methyl-5-phenylpenta-2,4-dienoates in high yields. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1839–1844, October, 1997.     

S<Subscript>(2)</Subscript>- or N<Subscript>(3)</Subscript>-Substituted 2-Mercapto-5-(4-pyridyl)-1,3,4-oxadiazoles

New S₍₂₎- or N₍₃₎-substituted 2-mercapto-5-(4-pyridyl)-1,3,4-oxadiazoles have been obtained and characterized. The direction of substitution depends on the structure of the initial reactants and the reaction conditions. The synthesis of several thiosemicarbazides has been effected from isonicotinic acid hydrazide.     

碘催化合成三乙基膦酰乙酸酯

首次报道了碘对M ichaelArbuzov重排反应的催化作用.以亚磷酸三乙酯与2-卤代乙酸乙酯为原料,碘作催化剂,反应温度80℃,反应时间2 h,三乙基膦酰乙酸酯的产率达到90%-98%.     

Green synthesis of the 1-substituted 1H-1, 2, 3, 4-tetrazoles over bifunctional catalyst based on copper intercalated into Mg/Al hydrotalcite modified magnetite nanoparticles

An effective one-pot, convenient process for the synthesis of 1- substituted 1H-tetrazoles from triethyl orthoformate, amines, and sodium azide is described using copper (II) doped and immobilized on functionalized magnetic hydrotalcite (Fe₃O₄/HT-NH₂ Cu^II) as a novel recyclable catalyst. The application of this catalyst allows the synthesis of a variety of tetrazoles in good to excellent yields in water. The new catalyst was characterized using Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), thermogravimetric analysis (TGA), vibration sample magnetometry (VSM) and inductively coupled plasma analysis (ICP-OES). This new procedure offers several advantages such as short operational simplicity, practicability, and applicability to various substrates and the absence of any tedious workup or purification. The loading amount of Cu^II (doped and immobilized) on functionalized magnetic hydrotalcite was indicated to be 4.66 mmol g⁻¹, obtained from the ICP-OES analysis. Also, the excellent catalytic performance, thermal stability, and separation of the catalyst make it an excellent heterogeneous system and a useful alternative to other heterogeneous catalysts. Also, the catalyst could be magnetically separated and reused six times without significant loss of catalytic activity.     

4-Hydroxy-2-quinolones 143. Synthesis,structure, and spectroscopic characteristics of ethyl 2-hydroxy-4-oxo-4H-pyrazino[1,2-<Emphasis Type="Italic">a</Emphasis>]pyrimidine-3-carboxylate

Condensation of aminopyrazine with triethyl methanetricarboxylate gave ethyl 2-hydroxy-4-oxo-4H-pyrazino[1,2-a]pyrimidine-3-carboxylate. According to X-ray analytical data the compound exists in the 2-hydroxy-4-oxo form in the crystal. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 411–419, March, 2008.     

Synthesis of Cytotoxic 4-Sulfonyl-, 4-Sulfonylthio-and 4-Sulfothioazetidinones-2

4-Sulfonylazetidinones-2 were synthesized by the reaction of DBU and organic halides on the esters of penicillin sulfones. 4-Sulfonylthio- and 4-sulfothioazetindinones-2 were synthesized by nucleophilic substitution of the 2-benzothiazolylthio groups in 4-(benzothiazolylthio)azetidinones-2 using sodium sulfinates or sodium hydrogen sulfite. A study of their cytotoxic activities revealed the anticancer effect of compounds containing methylsulfonylthio-, 4-tolylsulfonylthio-, and 4-methoxycarbonylamino-phenylsulfonylthio-substituents at position 4 of the -lactam ring relative to a wide range of monolayer cultures of cancer cells in vitro.     

Efficient and Convenient Method for the Synthesis of Symmetrical Triindolylmethanes Catalyzed by Iodine

Indoles reacted with triethyl orthoformate in the presence of a catalytic amount of iodine at room temperature to give the corresponding symmetrical triindolylmethanes (TIMs) in good to high yields.     

Synthesis and characterization of two new coordination supramolecular structures from a versatile unsymmetric 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) ligand

Two new inorganic–organic coordination networks based on a versatile and unsymmetric building block 5-(4-pyridyl)-1,3,4-oxadiazole-2-thione (Hpot) and inorganic Co^II and Cd^II salts have been synthesized in mixed solvent media and structurally characterized by single-crystal X-ray diffraction analysis. Crystal Hpot (1) was obtained from methanol solution. Reaction of Co(NO₃)₂ · 6H₂O with Hpot afforded a neutral two-dimensional (2-D) porous coordination polymer {[Co(pot)₂] · 6H₂O}_n (2) with a (4,4) network, which shows a 3-D supramolecular network through O–H?O weak interactions. While substituting the transition metal ions used in 2 with Cd(NO₃)₂ · 6H₂O, a neutral 2-D coordination polymer [Cd₂(pot)₄]_n (3) with a (6,3) network which further extended to a 3-D supramolecular structure through versatile hydrogen bonds C–H?X (X = O, N and S) was obtained. It is remarkable that the building block “pot” anion exhibits versatile coordination modes in complexes 2 and 3. These results indicate that the versatile nature of this rigid unsymmetric ligand, together with the coordination preferences of the metal centers, plays a critical role in construction of novel coordination polymers. The properties of gas absorption, magnetism and luminescence of 2 and 3 have been investigated and discussed in detail.     

The synthesis of bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides and other related 1,3,4-oxadiazoles from 1,1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters

Reactions of symmetrical 1,1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters in the presence of catalytic amount of glacial acetic acid resulted in the formation of three heterocyclic products: the appropriate bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides, 2-benzyl-1,3,4-oxadiazoles and 2-benzoyl-1,3,4-oxadiazoles. The presence of the latter two compounds is connected with carbon-sulfur fission in the molecule of the starting hydrazide. The identity of the unexpected fission products was confirmed by parallel syntheses of the model 1,3,4-oxadiazoles from phenylacetic acid hydrazide and 2-hydroxymethyl-1,3,4-oxadiazole derivatives.     

Electrochemical Oxidation of Catechols in the Presence of Triethyl Phosphite

The mechanism of electrochemical oxidation of catechol and some of its derivatives have been studied in the presence of triethyl phosphite as a nucleophile in aqueous solution. Voltammetric studies indicate that the quinones derived from catechol, and its derivatives, participate in Michael addition reaction with triethyl phosphite. The reaction mechanism consists of electron transfer followed by a chemical reaction which is named as an EC mechanism. The homogeneous rate constants (k_obs) were estimated by comparing the experimental cyclic voltammograms with the digitally simulated voltammograms based on EC mechanism. Also the effects of nucleophile concentration and substituted group of catechols on voltammetric behavior and the rate constants of chemical reactions were examined.     

Interactions of carborane-containing electrophiles with triethyl phosphite. Synthesis of new carborane-containing phosphonates

The reactions ofo-carboran-l-ylethyl mesylates with triethyl phosphite and sodium diethyl phosphite were studied. Carborane-containing phosphonates were synthesized. The reaction ofo-carboranylacetyl chloride with triethyl phosphite affordedO,O-diethyl (E)-2-(o-carboran-l-yl)-1-(o-carboran-1-ylacetoxy) vinylphosphonate rather than oxo phosphonate. Dedicated to the memory of Academician M. I. Kabachnik on his 90th birthday. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2041–2044, October, 1998.     

Convenient and Regioselective One‐Pot Solvent‐Free Synthesis of ß‐Hydroxyphosphonates

A simple, efficient, regioselective, and solvent‐free method has been developed for the synthesis of β‐hydroxyphosphonates from epoxides and triethyl phosphite using ZnCl₂ in high yields under mild conditions.     

Synthesis and Reactions of New Fused Heterocycles Derived from 5-Substituted-4-Amino-3-Mercapto-(4H)-1,2,4-Triazole with Biological Interest

The reaction of thiocarbohydrazide with carboxylic acids at the melting temperature allows an improved preparation of 5-substituted-4-amino-3-mercapto 1,2,4-triazoles 1 _{a ? g} . Compound 1 _a reacted with 2-bromopropionic acid to give acid derivative 2 . The latter was reacted with a mixture of acetic anhydride and triethylamine to afford the mesoionic compound 3 . Heating of compound 3 in ethanol gave the ester derivative 4 , which on alkaline hydrolysis in methanol gave ketone derivative 5 . Substituted 1,2,4-triazolo [3,4-b]-6H-1,3,4-thiadiazine 6 _h,i and 7 were synthesized by reaction of 1 _a with acetylacetone, ethyl acetoacetate and chloroacetamide. Heterocyclic systems 8 and 9 were prepared through the reaction of 1 _a with 2,3-dichloro-1,4-naphthoquinone and 2,3-dichloroquinoxaline. In addition, thenoyl isothiocyanate, thenoyl chloride, 2-thiophenecarbaldehyde, and p-chlorophenyl isocyanate reacted with compound 1 _a to afford 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazole ring system 10 , 11 , and urea derivative 12 . 1,2,4-Triazolo[3,4-b]-5H-pyrazole derivatives 14 _j,k were prepared through the reaction of compound 1 _a with 3-chloro-2,4-pentandione and ethyl-2-chloroacetoacetate. Compound 14 _j was treated with hydrazine to afford products 15 , 16 , and 17 depending on the type of hydrazine derivative and reaction conditions. Compound 19 was synthesized by refluxing of compound 14 _j with hydroxylamine hydrochloride to afford the corresponding oxime derivative 18 followed by treatment with thenoyl chloride.     

2-(5-取代苯氧甲基-1,3,4-噻二唑-2-亚胺基)-5-(取代苯基亚甲基)-4- 噻唑啉酮的合成

以2-氨基-5-取代苯氧甲基-1,3,4-噻二唑(1)为起始原料, 合成了中间体2-氯乙酰氨基-5-取代苯氧甲基-1,3,4-噻二唑)-2-乙酰亚胺(2)和2-(5-取代苯氧甲基-1,3,4-噻二唑-2-亚胺基)-4-噻唑啉酮(3), 化合物3进一步与取代苯甲醛发生类Knoevenagle缩合反应, 得到了一系列2-(5-取代苯氧甲基-1,3,4-噻二唑-2-亚胺基)-5-(取代苯基亚甲基)-4-噻唑啉酮类化合物4a～4p. 目标化合物4a～4p的结构经IR, ¹H NMR和元素分析确证.     

低价钛化合物催化合成咪唑烷的一锅合成法

本文报道了在低价钛催化下,亚胺类化合物和原甲酸三乙酯发生交叉偶联反应以适中产率制得咪唑烷类化合物,并对所得各种不同取代基的咪唑 烷基化合物的产率和异构体比例进行了讨论。产物的构型用核磁共振波谐进行了表征。