One‐Pot Synthesis of 4‐(2,3‐Dihydro‐2‐hydroxy‐1,3‐dioxo‐1H‐inden‐2‐yl)‐Substituted 1‐Aryl‐1H‐pyrazole‐3‐carboxylates via a Tandem Three‐Component Reaction

The hitherto unreported, highly functionalized 1H‐pyrazole‐3‐carboxylates 3 have been synthesized in good yields via a one‐pot three‐component domino reaction of phenylhydrazines, dialkyl acetylenedicarboxylates, and ninhydrin under mild conditions for the first time. No co‐catalyst or activator is required for this multicomponent reaction, and the reaction is, from an experimental point of view, simple to perform (Scheme 1). The structures of compounds 3 were corroborated spectroscopically (IR, ¹H‐ and ¹³C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this type of cyclization/addition reaction is proposed (Scheme 2).     

Efficient One‐Pot Synthesis of Alkyl 2‐(Dialkylamino)‐4‐phenylthiazole‐5‐carboxylates and Single‐Crystal X‐Ray Structure of Methyl 2‐(Diisopropylamino)‐4‐phenylthiazole‐5‐carboxylate

The reaction between secondary amines, benzoyl isothiocyanate, and dialkyl acetylenedicarboxylates (=dialkyl but‐2‐ynedioates) in the presence of silica gel (SiO₂) led to alkyl 2‐(dialkylamino)‐4‐phenylthiazole‐5‐carboxylates in fairly high yields. The structures of the products were confirmed by their IR, ¹H‐ and ¹³C‐NMR, and mass spectra, and by a single‐crystal X‐ray structure determination.     

C(aryl)?O Activation of Aryl Carboxylates in Nickel‐Catalyzed Biaryl Syntheses

Crucial breakthroughs in the activation of the C(aryl)? O bond of phenol derivatives were achieved almost simultaneously by two research groups (see scheme; Cy=cyclohexyl). Garg et al. coupled a range of aryl pivalates with arylboronic acids to give unsymmetrical biaryls. Shi et al. achieved this through C(aryl)? O activation of aryl carboxylates; the best results for the coupling of aryl boroxines were again obtained with aryl pivalates.

     

Facile synthesis of a tricyclohexylphosphine‐stabilized η3‐allyl‐carboxylato Ni(II) complex and its relevance in electrochemical butadiene carbon dioxide coupling

With the reaction of bis(1,5‐cyclooctadiene)nickel(0) and trans‐penta‐2,4‐dienoic acid in the presence of tricyclohexylphosphine, a new more general method was developed to synthesize cyclic π³‐allyl‐carboxylato Ni(II) complexes, which are known to be intermediates in the C? C coupling of butadiene and CO₂. The cyclic π³‐allyl‐carboxylato Ni(II) complex obtained is tested as a mediator in the electrochemical coupling reaction of butadiene and carbon dioxide. We also demonstrate the dependency on the coordination sphere by using platinum instead of nickel as the metal center. Copyright © 2005 John Wiley & Sons, Ltd.     

吡啶羧酸铬配合物的合成及其生物活性

报道了3种吡啶羧酸铬配合物的合成，其结构经元素分析、IR、’H—NMR和MS表征。以2-吡啶甲酸铬配合物饲喂猪的试验表明，它是一种很有效的饲料添加剂。     

One‐Pot Synthesis of (1,2,3‐Triazolyl)methyl 3,4‐Dihydro‐2‐oxo‐1H‐pyrimidine‐5‐carboxylates as Potentially Active Antimicrobial Agents

A simple and efficient one‐pot four‐component procedure has been developed for the synthesis of a wide range of compounds containing the (triazolyl)methyl oxo‐pyrimidine‐carboxylate system from propargyl β‐keto esters, various azides, aldehydes, and urea in the presence of catalytic amounts of (AcO)₂Cu/sodium ascorbate in AcOH. The method worked well with different aryl and heteroaryl aldehydes, and for a variety of substituents in the triazolyl part of the molecule. The antimicrobial activities of the products were evaluated against two Gram‐positive and Gram‐negative bacteria, and one fungus. Compound 5j was active against Staphylococcus aureus and Candida albicans.     

Unexpected Reaction Course of 3‐Amino‐5‐aryl‐1H‐pyrazoles with Dialkyl Dicyanofumarates

On treatment of 3‐amino‐5‐aryl‐1H‐pyrazoles 1 with dialkyl dicyanofumarates (=(E)‐but‐2‐enedioates) 4 in boiling 1,2‐dichloroethane, two competitive reactions occurred leading to 3‐aryl‐5‐cyano‐6,7‐dihydro‐6‐oxo‐1H‐pyrazolo[3,4‐b]pyridine‐4‐carboxylates 10 and 7‐amino‐2‐arylpyrazolo[1,5‐a]pyrimidine‐5,6‐dicarboxylates 11 . In DMF at room temperature, as well as at 100°, only compounds 10 were isolated. The formation of the major products of type 10 was rationalized via Michael addition of 1 as a C(4)‐nucleophile onto 4 , followed by HCN elimination and lactamization. On the other hand, the minor products 11 result from a Michael addition of 1 onto 4 via the NH₂ group, and subsequent HCN elimination and cyclization. The structures of the products have been established by X‐ray crystallography.     

Activated fly ash-catalyzed synthesis of naphthyl-substituted cyclohexenone carboxylates,indazolonols, and nitro hydrazones in “dry media”

Abstract

An efficient and rapid synthesis of an array of naphthyl-substituted cyclohexenone carboxylates, indazolonols, and nitrohydrazones by using activated fly ash as catalyst in dry media is described. All the synthesized compounds were characterized by their melting point, elemental analysis, mass spectrometry, Fourier transform infrared, one-dimensional nuclear magnetic resonance (¹H and D₂O exchanged ¹H and ¹³C), and two-dimensional homonuclear correlation (HOMOCOR) and heteronuclear single quantum coherence (HSQC) spectroscopic data. Compared to classical conditions, this new protocol had the advantage of excellent yields, mild reaction conditions, simple workup, and short reaction times. Also, the catalyst could be reused up to four runs without any reduction in efficiency, making the process greener and environmentally benign.      

Speciation of phenyltin(IV) compounds using high‐performance liquid chromatography. Part 2: The direct analysis of mixed standard solutions of triphenyltin halides/pseudohalide and of triphenyltin carboxylates containing functional group variations in the esteryl moiety

Simultaneous speciation of mixed standard solutions of triphenyltin halides (triphenyltin chloride, bromide, iodide) and pseudohalide (triphenyltin isothiocyanate) has been achieved with reversed‐phase high‐performance liquid chromatography on a Waters Spherisorb S5W ODS‐2 (octadecyl‐silica) column. An isocratic mixture of 95:5 (v/v) acetonitrile:water was used as the mobile phase at a flow rate of 1 ml min^?1. A series of selected triphenyltin carboxylates, Ph₃SnOCOZ, where Z = Me, Ph, CH:CHPh, CH:NOMe, CH₂SC₅H₄N and CH₂SC(S)NMe₂, was also similarly analysed using this system with two separate isocratic elutions using 100% acetonitrile and 96:4 (v/v) acetonitrile:water as the mobile phase. UV detection was done at 254 nm and the total run time for each analysis was less than 3 min. The detection limits for all the phenyltin(IV) compounds were in the range 0.01–0.03 ppm. Spiked water samples containing the triphenyltin carboxylates could also be simultaneously analysed by the above method without the need for any prior derivatization, following extraction with hexane. Pretreatment of the aqueous sample with NaCl/HCl and of the organic phase with hexamethylphosphoramide enabled recoveries of about 80% of the triphenyltins. Copyright © 2002 John Wiley & Sons, Ltd.