Synthesis of δ-carbolines via a Pd-catalyzed sequential reaction from 2-iodoanilines and N-tosyl-enynamines

A facile Pd-catalyzed sequential reaction has been developed for the synthesis of δ-carbolines from 2-iodoanilines and N-tosyl-enynamines. This protocol involves Larock heteroannulation/elimination/electrocyclization/oxidative aromatization cascade sequences and allows access to multisubstituted δ-carbolines in moderate to good yields.     

Rapid access to diverse α-carbolines through sequential transition metal catalyzed amination and direct C–H arylation

An efficient sequence of Pd catalyzed amination and direct C–H arylation for a synthesis of pharmacologically important α-carbolines is described. The outstanding feature in the synthetic sequence is that a combination of DBU and 2-(dicyclohexylphosphino)biphenyl (DCHPB) plays a critical role to not only enhance the reactivity but also suppress hydrodehalogenation in the direct C–H arylation step. The reaction protocol provides α-carbolines with various substituents including base-sensitive ester and ketone moieties in moderate to excellent yields. Moreover, combination with Cu catalyzed amination further enhanced the versatility of the α-carboline synthesis.     

Cu(I) metal organic framework catalyzed C–C and C–N coupling reactions

DABCO (1,4-diazabicyclo[2.2.2]octane) based Cu(I) metal organic framework (here after represented as Cu(I)-MOF) catalyzed Sonogashira cross-coupling reaction of iodobenzene and phenylacetylene was conducted smoothly to afford diphenylacetylene in excellent yield under N₂ atmosphere. For comparative study, piperidine based Cu(I) clusters were also investigated. Among these catalysts, Cu(I)-MOF exhibited higher activity with good selectivity for the C–C cross-coupled product. Cu(I) catalysts investigated in this study exhibited similar activity in the C–C homo-coupling reaction of phenylacetylene in O₂ atmosphere. Application of these catalysts was extended in the C–N coupling reactions between phenylboronic acid and aromatic/aliphatic/heterocyclic amines. Cu(I)-MOF can be readily recovered from the reaction mixture and reused for several cycles without loss in the catalytic activity.     

Straightforward access to oxazaborines, diazaborinones and triazaborines by reactions of β-enaminoamides with 4-methylbenzenediazonium tetraphenylborate

The reaction of substituted β-enaminoamides with 4-methylbenzenediazonium tetraphenylborate in dichloromethane produces besides the primary products of azo coupling reaction at the α-carbon atom of β-enaminoamides, also mixtures of heterocyclic compounds of boron: 1,3,2λ⁴-oxazaborines, 1H-1,3,2λ⁴-diazaborine-4-ones and 4H-1,2,4,3λ⁴-triazaborines. Proportions of the products change depending on the reaction conditions, particularly depending on the presence or absence of base (sodium acetate) in the reaction mixture. The heterocyclic compounds were separated chromatographically and identified by means of X-ray, ¹H, ¹¹B, ¹³C and ¹⁵N NMR spectra and elemental analyses.     

Recognition of α-Amino Acid from β- and γ-Amino Acid by N -Phosphorylation

The reactivity of N -phosphoryl f -alanine differs from N -phosphoryl g -alanine and N -phosphoryl n -amino butyric acid enormously. N -phospho- f -alanine could self-activate to yield N -phosphopeptides either in aqueous or nonaqueous media, but not g - or n -amino acid analogues. The mechanism of the reaction is discussed.     

Copper-catalyzed synthesis of N-aryl acridones from 2-amino benzophenones and aryl boronic acids via sequential double oxidative C–N coupling

Pot-economic synthesis of N-aryl acridones was performed with 2-aminobenzophenones and aryl boronic acids as starting materials. Cu-catalyzed chelation-assisted oxidative C–N cross-coupling reactions were well merged with the following intra-molecular oxidative dehydrogenative C–H amination reactions under an air atmosphere. The use of reagent capsules can further resolve the compatibility problem of reagents and simplify the operational process, providing a more straightforward access to the target products.     

Synthetic Approaches to α-, β-, γ-, and δ-Lycoranes

Lycorane is a pentacyclic core presented in alkaloids isolated from the Amaryllidaceae family of herbaceous flowering plants. Members of this class of natural products have shown to display important biological properties including analgesic, antiviral, and antiproliferative activities. This review presents the known synthetic routes toward α-, β-, γ-, and δ-lycoranes. α-(19 routes), β-(10 routes), γ-(38 routes), and δ-(6 routes).     

Diastereoselective synthesis of β- and γ2-muurolene: a carbocationic pathway from mono- to sesquiterpenes

The Lewis acid catalysed addition of the piperityl chlorides6 to isoprene yields adduct7, which undergoes a cis-stereoselective cyclisation to give the diastereoisomeric muurolene monohydrochlorides8. Treatment with potassium tert-butoxide affords β- and γ₂- muurolene 2.     

Biodegradation of α-, β-, and γ-Hexachlorocyclohexane by Arthrobacter fluorescens and Arthrobacter giacomelloi

The organochlorine pesticide γ-hexachlorocyclohexane (γ-HCH, lindane) and its non-insecticidal isomers α-, β-, and δ- continue to pose serious environmental and health concerns, although their use has been restricted or completely banned for decades. The present study reports the first results on the ability of two Arthrobacter strains, not directly isolated from a HCH-polluted site, to grow in a mineral salt medium containing α-, β-, or γ-HCH (100 mg?l^?1) as sole source of carbon. Growth of cultures and HCHs degradation by Arthrobacter fluorescens and Arthrobacter giacomelloi were investigated after 1, 2, 3, 4, and 7 days of incubation by enumerating colony forming units and GC with ECD detection, respectively. Both bacteria are able to metabolize the HCHs: A. giacomelloi is the most effective one, as after 72 h of incubation it produces 88 % degradation of α-, 60 % of β-, and 56 % of γ-HCH. The formation of possible persistent compounds was studied by GC/MS and by HPLC analysis. Pentachlorocyclohexenes and tetrachlorocyclohexenes have been detected as metabolites, which are almost completely eliminated after 72 h of incubation, while no phenolic compounds were found.     

Pd-catalyzed selective decarboxylation/C–H activation coupling of aryl acid with thiazole and oxazole directed by 1,2,3-triazole

An efficient palladium-catalyzed selective decarboxylation/C–H activation coupling of aryl acid with thiazole and oxazole under the assistance of 1,2,3-triazole ring were developed. This work provides an effective access to build functionalized 1,2,3-triazoles bearing thiazole and oxazole moieties. This method has good substrate compatibility to compose a series of selective heterocyclic compounds in moderate to good yields.     

Efficient CuCl-Catalyzed Selective and Direct Oxidation of β- and γ-Substituted Aliphatic Primary Alcohols to Carboxylic Acids

A new procedure for the selective and direct oxidation of aliphatic primary alcohols having substitution at β- and γ-positions to corresponding carboxylic acids was developed using a catalytic amount of ligand and additive-free CuCl with anhydrous ^t BuOOH in acetonitrile solvent under very mild reaction conditions. This procedure is very simple and mild and works efficiently without any additives at room temperature.     

Syntheses of amides via iodine-catalyzed multiple sp~3 C–H bonds oxidation of methylarenes and sequential coupling with N,N-dialkylformamides

<正>~~     

Efficient and convenient preparation of γ-nonalactone,with use of a Dean–Stark trap to remove methanol

We describe the development of an efficient and convenient process for preparation of γ-nonalactone. The synthesis was accomplished by free-radical addition of methyl acrylate and n-hexanol. A Dean–Stark trap filled with water and n-hexanol was used to remove the methanol generated during the process. Orthogonal experiments were performed to optimize the reaction conditions, and the desired product, γ-nonalactone, was produced in better than 70 % yield.     

Synthesis and characterization of α-, β-, and γ-Ga2o3 prepared from aqueous solutions by controlled precipitation

α, β and γ-Ga₂O₃ have been successfully obtained in an easily scalable synthesis using aqueous solution of gallium nitrate and sodium carbonate as starting materials without any surfactant and additive. α and β-Ga₂O₃ were obtained by calcination at 350 and 700 °С, respectively, of α-GaOOH, prepared by controlled precipitation at constant pH 6 and T = 55 °С, with 24 h of aging. Aging was necessary to fully convert the initially preciptated gel into a well-crystalline and phase-pure material. γ-Ga₂O₃ was obtained after calcination at 500 °С of gallia gel, synthesized at constant pH 4 and T = 25 °С, without aging. These three polymorphs have a for gallia relatively high surface area: 55 m²/g (α-Ga₂O₃), 23 m²/g (β-Ga₂O₃) and 116 m²/g (γ-Ga₂O₃). The combination of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), nitrogen physisorption and thermogravimetry (TG) was employed to characterize the samples and their formation.     

Enantioselective access to (−)-indolizidines 167B, 209D, 239AB, 195B and (−)-monomorine from a common chiral synthon

An enantioselective access to (?)-indolizidine alkaloids 167B, 209D, 239AB, 195B and (?)-monomorine from a new chiral synthon is described. The use of (S)-3-(Cbz-amino)-4-(tert-butyldimethylsilyloxy)butanal, obtained from l-aspartic acid, has provided efficient access of the indolizidine frame work through a Horner–Wadsworth–Emmons reaction and reductive cyclization as the key steps.     

Facile and efficient protocols for C–C and C–N bond formation reactions using a superparamagnetic palladium complex as reusable catalyst

Research on Chemical Intermediates - Facile and efficient protocols for some multicomponent coupling reactions such as the Suzuki reaction and synthesis of polyhydroquinoline and...     

Catalyst-free aza-Michael addition of azole to β,γ-unsaturated-α-keto ester: an efficient access to C–N bond formation

An efficient aza-Michael addition of azoles to β,γ-unsaturated-α-keto esters under room temperature conditions has been developed. In this conjugate addition, no additional catalyst is employed. Azole reacts with β,γ-unsaturated-α-keto ester smoothly to afford new C–N bond adducts in good to excellent yields (up to 96%).     

Intramolecular palladium-catalysed enolate arylation of 2- and 3-iodoindole derivatives for the synthesis of β-carbolines, γ-carbolines, and pyrrolo[3,4-b]indoles

The palladium-catalysed intramolecular α-arylation of carbonyl compounds with amino-tethered 2- and 3-iodoindoles provides a useful methodology for the synthesis of indolo-b-fused nitrogen heterocycles. A variety of substituted tetrahydro β- and γ-carbolines, and pyrrolo[3,4-b]indoles, have been prepared by means of this palladium-catalysed annulation process.     

Efficient and selective analytical method for the quantification of a β-adrenoceptor agonist,isoproterenol, by LC–MS/MS and its application to pharmacokinetics studies

Isoproterenol (ISO) is a synthetic catecholamine with a powerful cardiac stimulate, bronchial smooth and skeletal muscle relaxation, coronary artery and peripheral vasodilator effects. In this study, a simple, rapid, and selective liquid chromatography–tandem mass spectrometry has been developed for the determination of ISO in rat plasma. Proteins were precipitated in plasma samples with 0.1?g?mL^?1 trichloroacetic acid and the ISO/internal standard (IS) were separated on a C₈ column. The ISO was detected by a triple-quadrupole mass spectrometer with electrospray ionization source. The transitions of m/z 212.1?→?193.9 for ISO and m/z 285.2?→?193.2 for IS were conducted through multiple reaction monitoring mode. This method was linear over the range of 2–500?n?g?mL^?1. The intra- and inter-day assay precision were observed between 3 and 10%. The accuracy was within ±11%. Stability study results demonstrated that ISO was stable in the autosampler at 4°C for 24?hr, and for 8?hr at room temperature. Only one freeze–thaw cycle at ?80°C for 24?hr was found to be stable. The validated method was successfully applied to a pharmacokinetic study of ISO in rats following subcutaneous administration.     

Hydrolysis Reaction of N-Phosphoryl-α-, β- and γ-amino Acids Studied by HPLC

The hydrolysis reactions of N-（O,O＇diisopropyl）phosphoryl-L-α-alanine （DIPP-L-α-Ala）, N-（O,O＇diisopropyl）- phosphoryl-D-α-alanine （DIPP-D-α-Ala）, N-（O,O＇-diisopropyl）phosphoryl-β-alanine （DIPP-β-Ala） and N-（O,O＇-diisopropyl）phosphoryl-γ-amino butyric acid （DIPP-γ-Aba）, were studied by HPLC and their hydrolysis reaction kinetic equations were obtained. Under acid conditions, the reaction rate of DIPP-L-α-Ala was close to that of DIPP-D-α-Ala and the same rule was true between DIPP-β-Ala and DIPP-γ-Aba. Meantime, the reaction rate of DIPP-L/D-α-Ala was as 10 times as that of DIPP-β-Ala or DIPP-γ-Aba. Under basic conditions, the hydrolysis reactions of DIPP-β-Ala and DIPP-γ-Aba almost did not take place and the reaction rate of DIPP-L/D-α-Ala was about 1/10 of that under acid conditions. Moreover, theoretical calculation further illuminated the differences of the hydrolysis rate from the view of energy. The results would provide some helpful clues to why nature chose a-amino acids but not other kinds of analogs as protein backbones.