Concise Synthesis of Ring-Fission Metabolites of Epicatechin: 5-(3,4-Dihydroxybenzyl)dihydrofuran-2(3H)-one M6

The ring-fission metabolites of epicatechin, 5-(3,4-dihydroxybenzyl)dihydrofuran-2(3H)-one M6 and 3-methylated M6, were prepared from 3,4-dihydroxybenzaldehyde and furan-2(5H)-one using two new concise methods in excellent yields (three or two steps in 40–60% overall yield).     

One-Pot Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Derivatives with H2SO4 Supported on Silica Gel or Alumina

The one-pot condensation of aromatic aldehydes, β-dicarbonyl compounds, and urea or thiourea in the presence of H₂SO₄ supported on silica gel or alumina (80% m/m) in refluxing n-hexane produces 3,4-dihydropyrimidin-2(1H)-ones and their sulfur derivatives in high to excellent yields.     

An Efficient Synthesis of New 3,4-Dihydropyrimidin- 2(1H)-ones Incorporating a Phenyl Moiety at C-5 and C-6 Catalyzed by TMSCl and Co(OAc)2.4H2O

New 3,4-dihydropyrimidin-2-ones having a phenyl moiety at C-5 and C-6 have been prepared by a microwave-assisted Biginelli–like reaction by a three-component, one-pot condensation of an aromatic aldehyde, deoxybenzoin and urea, or thiourea using TMSCl and Co(OAc) ₂ .4H ₂ O as an efficient Lewis acid catalyst.     

Diprotodecarboxylation Reactions of 3,4-Dialkoxythiophene-2,5-dicarboxylic Acids Mediated by Ag2CO3 and Microwaves

An efficient and rapid method is reported to obtain 3,4-dialkoxythiophenes from 3,4-dialkoxythiophene-2,5-dicarboxylic acids through a diprotodecarboxylation reaction with Ag₂CO₃/AcOH as a catalytic system and microwave heating in dimethylsulfoxide (DMSO) as solvent. This methodology lets us obtain for the first time good performance with thiophenes bearing strong electron-donating groups such as alkoxides. This methodology eliminates the usage of harmful quinoline as solvent, as well as the long reaction times typically used (12–18 h) to obtain the 3,4-dialkoxythiophenes. The reaction of 7 diacids showed good yields (60–89%) following 20 min of microwave heating in a temperature range of 120–150 °C.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Reaction of NO at low temperature by ACF loading urea and rare-earth element oxides (La2O3, CeO2)

Loaded catalysts of 10–50% (w/w) urea loaded on activated carbon fibers (ACF), referred to as urea/ACF, and 10%urea–5–15% (w/w) La₂O₃/ACF and CeO₂/ACF were prepared by an impregnation method and used for removal of NO at low temperature (30–120°C). The experimental results showed that the catalytic activity of urea/ACF could be greatly improved by loaded rare-earth element oxides. Furthermore, 10%urea–5%La₂O₃/ACF and 10%urea–10%CeO₂/ACF could maintain high and stable catalytic activity at 100°C.     

Intramolecular C–H insertion catalyzed by dirhodium(II) complexes using CO2 as the reaction media

Abstract

In this work, the intramolecular C–H insertion of diazoacetamides catalyzed by dirhodium(II) complexes and using CO₂ as solvent is disclosed. The expected lactams were obtained in yields over 97%. The asymmetric intramolecular C–H insertion was also achieved and the β-lactam 14 was obtained in >97% yield and 65% ee using the chiral dirhodium(II) catalyst Rh₂(S-PTTL)₄. Finally, the dirhodium(II) complex Rh₂(OAc)₄ was used in two consecutive cycles in which complete conversion to the lactam was observed.     

Base-mediated one-pot synthesis of 3,4,5,6-tetrahydro-4-substituted benzo[h]quinazoline-2(1H)-thione derivatives and evaluation of their antioxidant activity

One-pot three-component Beginelli-like reactions of a ketone 1, an aryl aldehyde 2, and thiourea 3 in the presence of sodium hydroxide are described. In this reaction, 3,4,5,6-tertrahydro-4-substituted quinazoline-2(1H)-thione derivatives 4a–h were obtained in good yields (73–85%). The compound 4a has been characterized by single crystal X-ray analysis. All the synthesized compounds 4a–h and 5a–b were screened for their in vitro antioxidant activity. Compounds 4c, 4e, and 4h have exhibited an excellent than the standard ascorbic acid. Compounds 4d, 4f, and 4g have also shown good activity. Remaining compounds show moderate antioxidant activity.     

Synthesis of Novel New 2-(2-(4-((3,4-Dihydro-4-oxo-3-aryl quinazolin-2-yl)methyl)piperazin-1-yl)acetoyloxy)-2-phenyl Acetic Acid Esters

Stereoselective diazotization of (S)-2-amino-2-phenyl acetic acid (L-phenyl glycine) (4) with NaNO₂ in 6% H₂SO₄ in a mixture of acetone and water gave optically pure (S)-2-hydroxy-2-phenyl acetic acid (L-mandelic acid) (5). Esterification, gave (S)-2-hydroxy-2-phenyl acetic acid esters (6). The latter was treated with chloroacetyl chloride in the presence of triethylamine (TEA) in dichloromethane (DCM) to yield (S)-2-chloroacetyloxy phenyl acetic acid ester (2). In another sequence, the reaction of 2-(chloromethyl)-3-arylquinazolin-4(3H)-one (9) treated with N-Boc piperazine, followed by deprotection of the Boc group, to obtain 3-aryl-2-((piperazin-1-yl)methyl) quinazolin-4(3H)-one (3). Reaction of 2 with 3 in the presence of K₂CO₃ and KI gave the title compound, 2-(2-(4-((3,4-dihydro-4-oxo-3-arylquinazolin-2-yl)methyl)piperazin-1-yl) acetoyloxy)-2-phenyl acetic acid esters (1). The structures of all the new compounds obtained in the present work are supported by spectral and analytical data.     

Green synthesis of glycerol 1,3-bromo- and iodohydrins under solvent-free conditions

ABSTRACT

New eco-friendly conditions for Finkelstein reaction employing homogeneous media or alumina-supported reagents, both solventless, were utilized in the bromohydrins and iodohydrins synthesis from 1,3-dichlorohydrin (1,3-DCH), obtained from glycerol. Thus, the trans-halogenation of glycerol-1,3-dichlorohydrin (1) in homogeneous media, using NaI, NaBr salts and organic additives (TBAI, TBAB), led to the synthesis of four different glycerol halohydrins (2a, 2b, 3a, 3b) in regular to excellent conversions (43–96%) and good selectivities to 3a and 2b. Already, the alumina-supported reagents such as KI, KBr, NaBr were used for glycerol-1,3-dichlorohydrin trans-halogenation, in the absence of solvent, producing halohydrin mixtures in high conversions (77–99%) and very good selectivity (82%) to 1,3-diiodo-2-propanol (2b).     

NaHSO4·H2O as a Heterogeneous Acidic Reagent for Mild and Convenient Synthesis of 3,4-Dihydropyrimidin-2(1H)-ones and Their Sulfur Derivatives

One-pot cyclocondensation reaction of aromatic aldehydes, 1,3-dicarbonyl compounds and urea/thiourea in the presence of NaHSO₄·H₂O produced 4-aryl substituted 3,4-dihydropyrimidin-2(1H)-ones and their sulfur analogs in high to excellent yields. The reactions were carried out in refluxing n-hexane and were completed within 2.5–11 h.     

Synthesis,characterization, and investigations of antimicrobial activity of 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4(5H)-dione

Chalcone-like compounds 3a–l, 2-(benzylidene)-3,4-dihydronaphthalen-1(2H)-one, were synthesized from the addition of different benzaldehyde derivatives (2a–l) to 1,2,3,4-tetrahydro-1-napthalone (1) in basic medium. Mn(OAc)₃-mediated addition of dimedone (4) to chalcone-like compounds gave the spirobenzofuran derivatives (5a-l), 6,6-dimethyl-3-aryl-3′,4′,6,7-tetrahydro-1′H,3H-spiro[benzofuran-2,2′-naphthalene]-1′,4 (5H)-dione, in good yields. The structures of synthesized compounds 5a–l were elucidated on basis of spectral data (NMR, IR) and elemental analysis. In addition, their antibacterial activities were screened against some human pathogenic microorganisms.     

A green synthesis of 3,4-dihydropyrimidin-2-ones and 1,5-benzodiazepines catalyzed by Sn(HPO4)2.H2O nanodisks under solvent-free condition at room temperature

Abstract

Heterogeneous Tin (IV) hydrogen phosphate nanodisks [Sn(HPO4)2.H2O] efficiently catalyzed the one-pot three component condensation of aromatic aldehydes, β-ketoesters and urea to produce 3,4–dihydropyrimidin-2-ones under solvent-free conditions at room temperature. Also, the catalyst is equally applicable for the preparation of 1,5–benzodiazepines under the same reaction conditions. The optimum load of the catalyst required is 10 mole% and reusable. Hence, the process is green.

Solid‐Phase One Step Synthesis of 4H,4′‐Exomethylene‐bis[quinazolin‐2‐enols]

Abstract

The solid‐phase one step synthesis of 4H,4′‐exomethylene‐bis[quinazolin‐2‐enols] via 1,3‐dipolar cycloaddition of urea on benzylideneacetophenone using Sb(III) chloride impregnated alumina is described. The reaction provides 80–85% dimeric quniazolinenols. The process is convenient, cost‐effective and eco‐friendly.     

Supramolecular architecture built of Co(II) and a tripodal ligand containing 1-D water tapes with (H2O)16 cluster units

The reaction of Co(NO₃)₂?·?6H₂O with a tripodal ligand leads to a new complex {[Co(L)]?·?2NO₃?·?8H₂O} (1) confirmed by single-crystal X-ray diffraction, infrared spectroscopy, and elemental analysis. The particular interest of 1 is in the formation of a 1-D water tape consisting of (H₂O)₁₆ cluster units, the neighboring water tapes are connected by free nitrate anions via hydrogen bonds into a 2-D guest layer. These guest layers are alternately packed face-to-face with the 2-D host layers along the a-axis to form a 3-D supramolecular architecture. There exist C–H?···?N and C–H?···?O weak hydrogen bonds between the guest layer and host layer. These weak hydrogen bonds and water–nitrate, water–water hydrogen bonds are important for the stability of the overall structure.     

Efficient Room-Temperature Synthesis and Antimicrobial Study of Novel 2-Aroylbenzofuran-3-ols from Substituted Methyl Salicylates and Phenacyl Bromides

The article describes a convenient and efficient synthetic route for the construction of 2-aroylbenzofuran-3-ols from readily available diverse methyl salicylates and phenacyl bromides using K₂CO₃ as catalyst in dimethylformamide as solvent at room temperature. The reaction involves two steps, which occur in quick succession within 1 h to deliver the product with reasonably high yields. All the synthesized 2-aroylbenzofuran-3-ols (4a–u) were subjected for their antimicrobial studies, and some of these have shown prominent activity.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

TMSCl/Fe(NO3)3-Catalyzed Synthesis of 2-Arylbenzothiazoles and 2-Arylbenzimidazoles Under Ultrasonic Irradiation

A convenient one-pot cyclocondensation method for benzothiazole and benzimidazole syntheses is described. A set of benzothiazoles and benzimidazoles were readily prepared from aromatic ortho-diamines or ortho-aminothiophenol and aldehydes using chlorotrimethylsilane in dimethylformamide as promoter and water scavenger under ultrasonic irradiation in good yields (84–97%).     

Ultrasound-promoted green approach for the synthesis of multisubstituted pyridines using stable and reusable SBA-15@ADMPT/H5PW10V2O40 nanocatalyst at room temperature

ABSTRACT

A facile one-pot protocol for the synthesis of 2-amino-3-cyanopyridins using SBA-15@Triazine/H₅PW₁₀V₂O₄₀ as an efficient catalyst under ultrasonic conditions has been developed. The nanohybrid catalyst was prepared by the chemical anchoring of Keggin heteropolyacid H₅PW₁₀V₂O₄₀ onto the surface of SBA-15 mesoporous silica modified with 2-APTS -4,6-bis(3,5-dimethyl-1H-pyrazol- 1-yl)-1,3,5-triazine (ADMPT) linker. Then the nanohybrid was used as a green, efficient, eco-friendly, and highly recyclable catalyst for the one-pot and multi-component synthesis of 2-amino-3-cyanopyridin derivatives from the reaction of aldehydes, malononitrile, cyclic ketones and ammonium acetate under ultrasound waves with good to excellent yields (79–95%) and in a short span of time. This nanocatalyst was characterized by using FT-IR, XRD, SEM, TEM, BET, and EDX techniques.     

Reactions of pyridine-2-ethyl/methyl cyclopentadienes with metal carbonyls

Abstract

Thermal treatment of pyridine-2-ethyl cyclopentadiene (1) with Fe(CO)₅ and Ru₃(CO)₁₂ gave novel intramolecular C–H activated dinuclear products (3 and 5). In the case of Fe(CO)₅, the reaction also afforded the normal bis(cyclopentadienyl) diiron complex (4). However, similar reaction of pyridine-2-methyl cyclopentadiene (2) with Fe(CO)₅ and Ru₃(CO)₁₂ only afforded the normal bis(cyclopentadienyl) dinuclear metal complexes (7 and 8). For Ru₃(CO)₁₂, the reaction also yielded a pendant η¹-pyridyl-coordinated product (9). In addition, the reactions of 1 and 2 with Re₂(CO)₁₀ formed the corresponding pyridylethyl/pyridylmethyl cyclopentadienyl rhenium tricarbonyl complexes 10 and 11, which further underwent pyridine to rhenium cyclization via photoirradiation to provide the rhenium dicarbonyl complexes 12 and 13. The molecular structures of 3, 5, 6, 7, 8, 9, and 12 were determined by X-ray diffraction.     

Synthesis and characterization of a new cyclic phosph(V)azane ligand [(C6H5N)P(O)H]2 and its zinc(II) complex

The new cyclic phosph(V)azane ligand [(C₆H₅N)P(O)H]₂ (2) is obtained from the reaction between PCl₃ and PhNH₂ in toluene followed by controlled hydrolysis of the product in an H₂O–CHCl₃ solution. Compound 2 is the first example of P(V) dimer [(µ-NC₆H₅)P(H)=O]₂, a P₂N₂ ring with two P(O)H moieties. The reaction of 2 with ZnCl₂ in a molar ratio of 1?:?1 in tetrahydrofuran yields the cyclophosph(V)azane complex Cl₂Zn[(C₆H₅N)P(O)H]₂ (3) in which Zn–O bonds form directly between a cyclic phosph(V)azane ligand and Zn(II). The products have been characterized by infrared, multinuclear (¹H, ³¹P, ¹³C) NMR, mass spectrometry, and elemental analysis.     

Die Kristallstruktur von Dikalium-trikobalt(II)-dihydroxid-trisulfat-dihydrat,K2Co3(OH)2(SO4)3·2H2O

Crystals of K₂Co₃(OH)₂(SO₄)₃·2H₂O were synthesized under hydrothermal conditions. The crystal structure [a=17.945 (4) Å,b=7.557 (2) Å,c=9.760 (3) Å, space group Cmc2₁,Z=4] was determined by direct methods and refined with single crystal X-ray data. The H atoms were located byFourier syntheses. Their structural parameters were refined, too. The finalR-values areR=0.025 andR _w =0.028 (w=1/) for 612 reflections withF ₀>3 (F ₀). Both Co(II) atoms are octahedral six coordinated and form zigzag chains running parallel [001]. These chains are connected via sulfate groups to built up sheets parallel (100). The KO₉ polyhedron and one of the four hydrogen bonds link these sheets.