Mild and Efficient Syntheses of 1-Aryl-3,4-dihydroisoquinolines and 1-Aryl-3,4-dihydro-β-carbolines via Regiospecific β-Eliminations of the Corresponding N-Tosyl-1,2,3,4-tetrahydroisoquinolines and N-Tosyl-1,2,3,4-tetrahydro-β-carbolines

Treatment of N-tosyl-1-aryl-1,2,3,4-tetrahydro-isoquinolines or N-tosyl-1-aryl-1,2,3,4-tetrahydro-β-carbolines with a strong base such as NaOH or KOH at 70 °C in dimethylsulfoxide (DMSO) produced 1-aryl-3,4-dihydroisoquinolines or 1-aryl-3,4-dihydro-β-carbolines in good yields via mild and regiospecific β-eliminations. A dramatic solvent effect was observed, DMSO was crucial for the reactions. The temperature is also crucial for the reactions and should be kept between 60 and 80 °C.     

The Reaction of Electron-Deficient Cyclopropane Derivatives with Aromatic Amines

Abstract

N-Aryl-trans,trans-α-carboxyl-β-benzoyl-γ-aryl-γ-butyrolactams were synthesized in high yields with high stereoselectivity by the reaction of electron-deficient cyclopropane derivatives, cis-1-benzoyl-2-aryl-6,6-dimethyl-5,7-dioxo-spiro-[2 (a) Zhang , J. ; Blazecka , P. G. ; Davidson , J. G. First direct reductive amination of mucochloric acid: A simple and efficient method for preparing highly functionalized α,β-unsaturated γ-butyrolactams . Org. Lett. 2003 , 5 , 553 – 556 ; (b) Sarma, K. D.; Zhang, J.; Curran, T. T. Novel synthons from mucochloric acid: The first use of α,β-dichloro-γ-butenolides and γ-butyrolactams for direct vinylogous aldol addition. J. Org. Chem. 2007, 72, 3311–3318 . [Google Scholar] 5 (a) Chen , Y. L. ; Ding , W. Y. A simple approach to highly stereoselective synthesis of β γ-trans-γ-butyrolactones . Chem. J. Chin. Univ. 1998 , 19 , 1614 – 1616 ; (b) Chen, Y. L.; Ding, W. Y.; Cao, W. G.; Lu, C. Stereoselective synthesis of N-aryl-trans,trans-α-carboxyl-β-methoxycarbonyl-γ-aryl-γ-butyrolactones. Synth. Commun. 2002, 32, 1953–1960.  [Google Scholar]]-4,8-octadiones, with aromatic amines. The reaction mechanism was proposed.     

New Strategy for Synthesis of the Disaccharide Moiety of the Highly Potent Anticancer Natural Product OSW-1

The facile synthesis of a partially protected OSW-1 disaccharide moiety, having a 2-O-p-methoxybenzoyl-β-D-xylopyranosyl-(1 → 3)-2-O-acetyl-L-arabinopyranoside structure, was elaborated by glycosylation in a β-stereoselective fashion. The xylopyranose donors were synthesized by a short synthetic approach via convenient selective 1,2-diacetal protection of 3,4-trans-diequatorial hydroxyl group. Regioselective ring opening of 1,2-diacetal-protected substrates efficiently led to the arabinopyranose acceptor with a free 3-hydroxyl group. Glycosylation of the xylopyranose donor with the arabinopyranose acceptor provided the β-disaccharide.     

Microwave-assisted catalyst-free synthesis of tetrasubstituted pyrroles using dialkyl acetylenedicarboxylates and monophenacylanilines

An efficient catalyst-free microwave-assisted synthesis of tetrasubstituted pyrroles using dialkyl acetylenedicarboxylates and substituted monophenacylanilines has been developed. Axial chirality has been noticed in some N-(α-naphthyl/2-isopropylphenyl)-2,3-dicarbethoxy-4-arylpyrroles, but not with N-aryl-2,3-dicarbethoxy-4-(α-naphthyl)pyrrole.     

Stereoselective synthesis of novel monocyclic trans-3-halogenated-4-pyrazolyl-β-lactams: Potential synthons and promising biologically active agents

Stereoselective synthesis of novel monocyclic trans-3-halogenated-4-pyrazolyl-β-lactams 5 is described. The reaction of ketene derived from α-bromo/chloroethanoic acids 4 using POCl₃ and Et₃N with pyrazolyl substituted imines 3a–d in refluxing toluene resulted exclusive formation of trans-β-lactams through [2?+?2] through cycloaddition reaction. The chemical structures of all the newly synthesized β-lactams were verified on the basis of spectroscopic techniques such as FTIR, ¹H NMR, ¹³C NMR, and elemental analysis (CHN). The trans configuration of β-lactams 5 was assigned with respect to position of C3-H and C4-H. The novel β-lactams 5 are potential synthons for azetidines, aziridines, 3-unsubstituted azetidinones, 3-alkyl-halo-azetidinones, and promising biologically active agents.     

Facile synthesis of novel α-methylene-pyrazole-carboxylate substituted imines and trans-β-lactams: Versatile synthons for diverse heterocyclic molecules

A simple, facile, and high yielding stereoselective approach for the integration of α-methylene-pyrazole-carboxylates at the β-lactam nucleus is described. These monocyclic β-lactams have been synthesized by treatment of 2-phenoxy/benzylthio/phenylthio ethanoic acids or acetoxyacetyl chloride/phthalimidoacetyl chloride 5a–e with novel α-methylene-pyrazole-carboxylate imines 4a–c using Et₃N and POCl₃ in refluxing toluene. All of the newly synthesized α-methylene-pyrazole carboxylate imines 4a–c and their β-lactam derivatives 6a–h have been fully characterized by spectroscopic techniques such as FTIR, NMR (¹H, ¹³C, and ¹³C DEPT-135), 2D-NMR (COSY and HSQC), and elemental analyses (CHN). The cycloaddition reaction was found to be highly stereoselective leading to the exclusive formation of trans-β-lactams 6a–h and trans configuration was assigned with respect to coupling constant values of C3-H and C4-H. The novel β-lactams 6a–h bearing α-methylene-pyrazole-carboxylate ring system will serve as useful synthons for highly functionalized acids, acetohydrazides/pyrazolones, alcohols, pyrazole carboxamides, peptides, and promising biologically active agents.     

Synthesis,X-ray crystallographic studies,DFT calculations and nanostructural features of annulated imidazo[4,5-b]pyridine derivatives

Friedländer-type condensation of 5-amino-4-cyano-1-(phenyl/p-substitutedphenyl)imidazole with cycloalkanone was done by refluxing the mixture with a suspension of anhydrous aluminum chloride in dry 1,2-dichloroethane to produce 7-amino-3-aryl(5,6)cycloalkanoimidazolo[4,5-b]pyridine. Single X-ray crystallographic diffraction studies had shown that compounds had different types of heterodimeric, homodimeric π–π stacking, T-type stacking, and intermolecular hydrogen bonds which lead to nanostructure formation detected by scanning electron microscope. DFT calculation had also been performed to quantify heterodimeric π–π and T-stacking interactions.     

Fluorimetric Determination of p -Hydroxybenzoic Acid in Beer as α -Cyclodextrin Inclusion Complex

Abstract

The inclusion complex of p-hydroxyenzoic acid and α- and β-cyclodextrin has been studied by fluorescence spectroscopy. To describe quantitatively complex formation between α-cyclodextrin (α-CD) and p-hydroxybenzoic acid, an association constant of 967 ± 14 M^?1 at 21°C was obtained. The inclusion complex has been used to determine p-hydroxybenzoic acid in the range 0.15–1.00 mg L^?1 (RSD 4.5%, n = 8). Application of the method to determination of p-hydroxybenzoic acid in beer samples gave an endogenous content of 1.25 mg L^?1.     

Microwave-Accelerated Ruthenium-Catalyzed [2π + 2π] Cycloadditions of Dimethylacetylene Dicarboxylate with Norbornenes

An efficient and convenient procedure has been developed for the ruthenium-catalyzed [2π + 2π] cycloadditions of dimethylacetylene dicarboxylate with norbornenes. Reaction is significantly accelerated in microwave conditions, while the commonly used benzene solvent was replaced by environmentally benign tetrahydrofuran.

Synthesis and in Vitro Antimicrobial Activity of 3-Aryl-4-S-benzyl-6-phenylimino-2-hepta-O-acetyl-β-D-lactosylimino-2,3-dihydro-1,3,5-thiadiazine (Hydrochloride)

The present work includes synthesis of several 3-aryl-4-S-benzyl-6-phenylimino-2-hepta-O-acetyl-β-D-lactosylimino-2,3-dihydro-1,3,5-thiadiazines (hydrochloride) by the interaction of N-hepta-O-acetyl-β-D-lactosyl isocyanodichloride and 1-aryl-5-phenyl-2-S-benzyl-2,4-isodithiobiurets. All these products have been characterized through the usual chemical transformations and infrared, ¹H NMR, and mass spectral analysis. The compounds were also screened for their antimicrobial activities.     

Selective Bromination of Dehydroacetic Acid with N-Bromosuccinimide

Bromination of dehydroacetic acid has been carried out with N-bromosuccinimide under various conditions. The reactions led to selective bromination, thereby offering efficient synthesis of 3β-bromodehydroacetic acid (3), 3β,5-dibromodehydroacetic acid (4), 3β,3β-dibromodehydroacetic acid (5), and 3β,3β,5-tribromodehydroacetic acid (6).     

Modified One-Pot Multicomponent Diastereoselective Synthesis of Trans-2,3-Dihydrofuro[3,2-c]coumarins via In Situ–Generated α-Tosyloxyketones

A modified protocol for diastereoselective synthesis of differently substituted trans-2,3-dihydrofuro[3,2-c]coumarins is developed via, a one-pot multicomoponent reaction starting from aromatic aldehydes, 4-hydroxycoumarin, and α-tosyloxyacetophenones with pyridine and triethylamine as catalysts. The developed protocol provides a better alternative to the existing methods as it involves utilization of α-tosyloxyacetophenones that may be generated in situ from acetophenones and [hydroxyl(tosyloxy)iodo]benzene (HTIB, Koser's reagent), avoiding the use of α-haloacetophenones.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.     

SmI3-Catalyzed Addition of Amines to α,β-Unsaturated N-Acylbenzotriazoles

The addition of amines to α,β-unsaturated N-acylbenzotriazoles could be catalyzed by samarium triiodide (SmI₃) at ambient temperature. α,β-Unsaturated aliphatic N-acylbenzotriazoles afforded bis-addition products (β-amino amides), whereas N-cinnamoylbenzotriazoles gave acylated products (cinnamoylamides) exclusively.     

Simultaneous Chiral Separation of Geometry Isomers and Enantiomers of Nateglinide by Capillary Electrophoresis with Mixture of CD Derivations as Chiral Selector

Abstract

A capillary electrophoresis (CE) method for the simultaneous separation of geometry isomers and enantiomers of nateglinide was built. Several different dyclodextrin (CD) derivatives were tested for the chiral separation of nateglinide, and it was proved that ionic CDs [i.e., carboxymethy-β-CD (CM-β-CD) and sulphonic-β-CD (S-β-CD)] could show better chiral selectivity for both geometry isomers and enantiomers than the neutral CDs. The separation of geometry of both isomers and enantiomers of nateglinide was obtained by CE in a 75-µm i.d. × 60 cm (effective length 45 cm) fused-silica capillary at 11 kV voltage, while 30 mM phosphate (pH = 8.38) acted as running buffer and a mixture of 40 mM S-β-CD + 21 mM CM-β-CD served as chiral selector. The detective wavelength was set at 254 nm.     

Synthesis of Drim-7,9(11)-diene and Its Hydroxylated Derivatives

This article describes a new efficient synthesis of drim-7,9(11)-diene and its hydroxylated derivates from drim-8-en-7-one. Reduction of this ketone with NaBO₄ in the presence of CeCl₃ · 7H₂O afforded regio- and stereoselectively drim-8-en-7β-ol in a high yield. Its dehydration with H₂SO₄ under mild conditions led to drim-7,9(11)-diene. Noncatalytic oxidation of drim-7,9(11)-diene with OsO₄ and the catalytic oxidation with the pair OsO₄–NMO gave, in a high yield, depending on conditions, driman-7β,8β,9α,11-tetraol or its mixture with drim-7-en-9α,11-diol and drim-9(11)-en-7α,8α-diol. Under optimal conditions the total yield of these diols reached 89%. The separate, noncatalytic oxidation of drim-7-en-9α,11-diol and of drim-9(11)-en-7α,8α-diol with OsO₄ afforded driman-7α,8α,9α,11-tetraol.     

Study of Aqueous Biomolecules with Magnetic Flux Using Density,Viscosity, and Surface Tension Probe at 304.15 K

Doses of 0.0150 weber m^?2 magnetic flux for 30 minutes are given to four series of biomolecules in aqueous medium, densities (ρ), viscosities (η), and surface tension (γ) were measured at 304.15 K. The vitamins and carbohydrates decrease densities and viscosities and the difference of density from magnet to aqueous solution in order of dextrose (? 0.00025 kg m^?3) > fructose (? 0.00021 kg m^?3) = B6 (? 0.00021 kg m^?3) > starch (? 0.00018 kg m^?3) > B1 (? 0.0018 kg m^?3), while viscosity in order of starch (? 0.0044 kg m^?1s^?1) > fructose (? 0.0037 kg m^?1s^?1) > B1(? 0.0018 kg m^?1s^?1) > dextrose (? 0.0016 kg m^?1s^?1) > B6 (? 0.0012 kg m^?1s^?1). The surface tension also decreases in vitamin and carbohydrate. The proteins show increase in ρ, η, and γ value hence casein decrease the density and viscosity. The glutamine show increase in density and surface tension while decrease in viscosity and vice versa to alanine. These orders of the data indicate the intermolecular force between water and bimolecules in magnetic flux.     

Diastereoselective synthesis of novel 3-aryloxy/alkoxy-4-benzothiazolylpyrazolyl-β-lactams: Potential synthons for novel aminoacids/nanocopolymers

A fast, efficient, and diastereoselective synthesis of novel 3-oxo-4-benzothiazolylpyrazolyl-β-lactams is described. The reaction between 2-aryloxy/alkoxyacetic acid and novel benzothiazolylpyrazole-substituted imines afforded exclusive formation of trans-β-lactams. The scope of the reaction was investigated by varying different groups on substrates (R¹, R², R³, Z). All the novel compounds were characterized using various spectroscopic techniques such as FT-IR, ¹H NMR, ¹³C NMR, elemental analysis, and mass spectrometry in representative cases. No report has been listed in the literature for the synthesis of these types of β-lactam heterocycles so far.     

Synthesis,characterization and XRPD studies of the bioactive complex of 2-hydroxy-3,5-dimethyl acetophenoneoxime (HDMAOX) with oxovanadium(IV)

The complex of 2-hydroxy-3,5-dimethyl acetophenoneoxime (HDMAOX, HL) with VO(IV) has been synthesized and characterized by different physical techniques. Infrared spectra indicate deprotonation and coordination of the phenolic OH, and nitrogen of the oximino group. Electronic spectra and magnetic susceptibility measurements support square-pyramidal geometry around the metal ion. The elemental analyses and mass spectral data indicate ML₂ composition. Thermodynamic activation parameters were computed from the thermal data using the Coats and Redfern method. The crystal data for C₂₀H₂₄N₂O₅V are: tetragonal, space group P4/m, a?=?11.76975?Å, b?=?11.76975?Å, c?=?18.89209?Å, V?=?2617.06?A³, Z?=?4. The free ligand (HDMAOX) and its oxovanadium complex have been tested in vitro against Alternaria alternate, Aspergillus flavues, Aspergillus nidulans and Aspergillus niger fungi and Streptococcus, Staph, Staphylococuss and Escherchia coli bacteria in order to assess their antimicrobial potential. The results indicate that the ligand and its metal complex have antimicrobial properties.     

Ammonium Chloride–Catalyzed One-Pot Synthesis of Tetrahydrobenzo[α]xanthen-11-one Derivatives Under Solvent-Free Conditions

A one-pot, multicomponent reaction of aldehydes, dimedone, and β-naphthols is described for the preparation of 12-aryl- or 12-alkyl-8,9,10,12-tetrahydrobenzo[α]xanthen-11-one derivatives using ammonium chloride as a mild, inexpensive, and environmentally benign catalyst under solvent-free conditions. Different types of aldehyde and β-naphthol derivatives are used in the reaction, and in all cases the products were synthesized successfully.

Fe-Mediated S–S Bond Cleavage and Its Application in the Synthesis of α-Arylthio Carbonyl Compounds

In the presence of iron dust, diaryl disulfides react with α-bromo carbonyl compounds to obtain α-arylthio carbonyl compounds in good yield at 90 °C under an N₂ atmosphere, using commercial dimethylformamide (DMF) as solvent. The possible reaction mechanism is that the disulfide is reduced by iron dust to give ArSFeSAr and then reacted with α-bromo carbonyl compounds to give product α-arylthio carbonyl compounds and FeBr₂.