Alcohols as Alkyl Electrophiles for Deoxygenative Heck Reaction Enabled by Excited State Pd Catalysis.

Here, we present a general method for the photoinduced Pd-catalyzed deoxygenative Heck reaction of vinyl arenes with -iodophenyl-thionocarbonate derived from alcohols. Mechanistic studies reveal that the deoxygenation involves a 5--trig cyclization and fragmentation process, with radical addition identified as the rate-determining step in this transformation. This one-pot procedure demonstrates excellent selectivity for less hindered hydroxyl groups in diols, facilitating late-stage functionalization of complex molecules and scalability to gram-scale synthesis.

1,2-Amidoarylcarbonylation of Styrenes to Access β-Acylamino Ketones by NHC-Catalyzed Radical Relay.

An amidoarylcarbonylation reaction of aromatic aldehydes and olefins with Katritzky pyridinium salts by N-heterocyclic carbene (NHC)-catalyzed radical relay to construct C-C and C-N bonds with good functional group tolerance is developed for the synthesis of β-acylamino ketones. This gentle and efficient approach offers a valuable style for the synthesis of β-acylamino ketones. Mechanistic studies revealed that a radical addition/coupling/elimination cascade process was involved in this reaction.

Photoinduced Triphenylphosphine and Iodide Salt Promoted Reductive Decarboxylative Coupling.

The transient electron donor-acceptor (EDA) complex has been an emerging area in the photoinduced organic synthesis field, generating radicals without exogenous transition-metal or organic dye-based photoredox catalysts. The catalytic platform to form suitable photoactive EDA complexes for photochemical reduction reactions remains underdeveloped. Herein, a general photoinduced reductive alkylation via the EDA complex strategy is described.

Photoredox-Catalyzed Allylic Defluorinative Alkoxycarbonylation of Trifluoromethyl Alkenes through Intermolecular Alkoxycarbonyl Radical Addition.

The -difluoroalkene moiety is an ideal carbonyl bioisostere in medicinal chemistry, but efficient synthesis of β--difluoroalkene esters remains challenging so far. Herein, we disclose a photoredox-catalyzed allylic defluorinative alkoxycarbonylation of trifluoromethyl alkenes enabled by intermolecular alkoxycarbonyl radical addition. A wide variety of alcohol oxalate derivatives were amenable, affording various β--difluoroalkene esters with excellent functional group tolerance.

Photoinduced Deaminative Alkylation for the Synthesis of γ-Ketoesters via Electron Donor-Acceptor Complex Formation.

Visible-light-induced deaminative alkylation of Katritzky salts with silyl enol ethers has been developed. The reaction can proceed efficiently through electron donor-acceptor complex formation, avoiding the use of precious metal complexes or synthetically elaborate organic dyes. A series of functionalized γ-ketoesters was successfully obtained with good functional group tolerance and compatibility under mild and straightforward conditions.

Transition-metal-free decarboxylative thiolation of stable aliphatic carboxylates.

A transition-metal-free decarboxylative thiolation protocol is reported in which primary, secondary, tertiary (hetero)aryl acetates and α-CN substituted acetates undergo the decarboxylative thiolation smoothly, to deliver a variety of functionalized aryl alkyl sulfides in moderate to excellent yields. Aryl diselenides are also amenable substrates for construction of C-Se bonds under the simple and mild reaction conditions. Moreover, the protocol is successfully applied to the late-stage modification of pharmaceutical carboxylates with satisfactory chemoselectivity and functional-group compatibility.

Triphenylphosphine-Catalyzed Alkylative Iododecarboxylation with Lithium Iodide under Visible Light.

Under irradiation of 456 nm blue light-emitting diodes, PPh catalyzes the iododecarboxylation of aliphatic carboxylic acid derived -(acyloxy)phthalimide with lithium iodide as an iodine source. The reaction delivers primary, secondary, and bridgehead tertiary alkyl iodides in acetone solvent, and the alkyl iodide products were easily used to generate C-N, C-O, C-F, and C-S bonds to allow various decarboxylative transformations without using transition-metal or organic-dye-based photocatalysts.

Nickel-catalyzed carboxylation of aryl iodides with lithium formate through catalytic CO recycling.

A protocol for the Ni-catalyzed carboxylation of aryl iodides with formate has been developed with good functional group compatibility for the synthesis of a variety of aromatic carboxylic acids under mild conditions. The reaction tolerates other functionalities for cross-coupling, such as aryl bromide, aryl chloride, aryl tosylate, and aryl pinacol boronate. The reaction proceeds through a carbonylation process with in situ generated carbon monoxide in the presence of a catalytic amount of acetic anhydride and lithium formate, avoiding the use of gaseous CO.

Photocatalytic decarboxylative alkenylation of α-amino and α-hydroxy acid-derived redox active esters by NaI/PPh catalysis.

Herein, we report the photocatalytic decarboxylative alkenylation reactions of N-(acyloxy)phthalimide derived from α-amino and α-hydroxy acids with 1,1-diarylethene, and with cinnamic acid derivatives through double decarboxylation, using sodium iodide and triphenylphosphine as redox catalysts. The reaction proceeds under mild irradiation conditions with visible blue light (440 nm or 456 nm) in an acetone solvent without recourse to transition-metal or organic dye based photoredox catalysts. The reaction proceeds via photoactivation of a transiently self-assembled chromophore from N-(acyloxy)phthalimide and NaI/PPh3.

Development of a dynamic feeding strategy for continuous-flow aerobic granulation and nitrogen removal in a modified airlift loop reactor for municipal wastewater treatment.

This study investigated the aerobic sludge granulation and nitrogen removal performance in a modified airlift loop reactor treating municipal wastewater under different operation conditions. Dynamic feeding and aeration control were applied to create feast/famine conditions to facilitate microbial aggregation. Experimental results demonstrated that aerobic granular sludge could be cultivated in continuous-flow reactors fed with an optimized dynamic feeding condition.

Photocatalytic decarboxylative alkylations mediated by triphenylphosphine and sodium iodide.

Most photoredox catalysts in current use are precious metal complexes or synthetically elaborate organic dyes, the cost of which can impede their application for large-scale industrial processes. We found that a combination of triphenylphosphine and sodium iodide under 456-nanometer irradiation by blue light-emitting diodes can catalyze the alkylation of silyl enol ethers by decarboxylative coupling with redox-active esters in the absence of transition metals. Deaminative alkylation using Katritzky's N-alkylpyridinium salts and trifluoromethylation using Togni's reagent are also demonstrated.

Efficient Pd-Catalyzed Regio- and Stereoselective Carboxylation of Allylic Alcohols with Formic Acid.

Formic acid is efficiently used as a C1 source to directly carboxylate allylic alcohols in the presence of a low loading of palladium catalyst and acetic anhydride as additive to afford β,γ-unsaturated carboxylic acids with excellent chemo-, regio-, and stereoselectivity. The reaction proceeds through a carbonylation process with in situ-generated carbon monoxide under mild conditions, avoiding the use of high-pressure gaseous CO. A bisphosphine ligand with a large bite angle (4,5-bis{diphenylphosphino}-9,9-dimethylxanthene, Xantphos) was found to be uniquely effective for this transformation.

Photoredox-Catalysed Decarboxylative Alkylation of N-Heteroarenes with N-(Acyloxy)phthalimides.

An iridium photoredox catalyst in combination with either a stoichiometric amount of Brønsted acid or a catalytic amount of Lewis acid is capable of catalyzing regioselective alkylation of N-heteroarenes with N-(acyloxy)phthalimides at room temperature under irradiation. A broad range of N-heteroarenes can be alkylated using a variety of secondary, tertiary, and quaternary carboxylates. Mechanistic studies suggest that an Ir /Ir redox catalytic cycle is responsible for the observed reactivity.

Mechanism of Boron-Catalyzed N-Alkylation of Amines with Carboxylic Acids.

Mechanistic study has been carried out on the B(C6F5)3-catalyzed amine alkylation with carboxylic acid. The reaction includes acid-amine condensation and amide reduction steps. In condensation step, the catalyst-free mechanism is found to be more favorable than the B(C6F5)3-catalyzed mechanism, because the automatic formation of the stable B(C6F5)3-amine complex deactivates the catalyst in the latter case.

Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids.

A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet.

Bacterial pyridine hydroxylation is ubiquitous in environment.

Ten phenol-degrading bacterial strains were isolated from three geographically distant environments. Five of them, identified as Diaphorobacter, Acidovorax, Acinetobacter (two strains), and Corynebacterium, could additionally transform pyridine, through the transcription of phenol hydroxylase genes induced both by phenol and pyridine. HPLC-UV and LC-MS analyses indicated that one metabolite (m/e = 96.

Simultaneous degradation of phenol and n-hexadecane by Acinetobacter strains.

Three phenol- and alkanes-degrading bacterial strains were isolated from a freshwater sample. Upon the 16S rRNA gene analysis, phenotype and physiological features, the three strains were designated as Acinetobacter sp. with both phenol hydroxylase gene (phe) and alkane monooxygenase gene (alkM) detected.

Efficient decentralized iterative learning tracker for unknown sampled-data interconnected large-scale state-delay system with closed-loop decoupling property.

In this paper, an efficient decentralized iterative learning tracker is proposed to improve the dynamic performance of the unknown controllable and observable sampled-data interconnected large-scale state-delay system, which consists of N multi-input multi-output (MIMO) subsystems, with the closed-loop decoupling property. The off-line observer/Kalman filter identification (OKID) method is used to obtain the decentralized linear models for subsystems in the interconnected large-scale system. In order to get over the effect of modeling error on the identified linear model of each subsystem, an improved observer with the high-gain property based on the digital redesign approach is developed to replace the observer identified by OKID.

Degradation of pyridine by one Rhodococcus strain in the presence of chromium (VI) or phenol.

A Rhodococcus strain, Chr-9, which has the ability to degrade pyridine and phenol and reduce chromium (VI) (Cr (VI)) was isolated. The strain could grow with pyridine as the sole carbon and nitrogen source, and its pyridine-degradation capability was enhanced by 100 mg l(-1) phenol; however, the degradation of pyridine was inhibited when the phenol concentration was greater than 400 mg l(-1). The hydroxylation of pyridine suggested that the stimulation and inhibition of phenol to the pyridine degradation may be attributed to competition of phenol and pyridine for the hydroxylase gene.

[Discrimination of bamboo fiber and ramie fiber by near infrared spectroscopy].

The research on discrimination of natural bamboo fiber, bamboo pulp fibers and ramie fiber used in textile was demonstrated by near infrared (NIR) spectroscopy. First, the spectra of three kinds of fiber were scanned by NIR spectrometer. Then, the spectral data were pretreated by first derivatives.

The nature of actinomycin D binding to d(AACCAXYG) sequence motifs.

Earlier studies by others had indicated that actinomycin D (ACTD) binds well to d(AACCATAG) and the end sequence TAG-3' is essential for its strong binding. In an effort to verify these assertions and to uncover other possible strong ACTD binding sequences as well as to elucidate the nature of their binding, systematic studies have been carried out with oligomers of d(AACCAXYG) sequence motifs, where X and Y can be any DNA base. The results indicate that in addition to TAG-3', oligomers ending with XAG-3' and XCG-3' all provide binding constants > or =1 x 10(7) M(-1) and even sequences ending with XTG-3' and XGG-3' exhibit binding affinities in the range 1-8 x 10(6) M(-1).

Unique actinomycin D binding to self-complementary d(CXYGGCCY'X'G) sequences: duplex disruption and binding to a nominally base-paired hairpin.

Actinomycin D (ACTD) has been shown to bind weakly to the sequence -GGCC-, despite the presence of a GpC site. It was subsequently found, however, that d(CATGGCCATG) binds relatively well to ACTD but exhibits unusually slow association kinetics, contrary to the strong-binding -XGCY- sites. In an effort to elucidate the nature of such binding and to delineate the origin of its interesting kinetic behavior, studies have now been extended to include oligomers with the general sequence motifs of d(CXYGGCCY'X'G)(2).

Solution structure of the ActD-5'-CCGTT3GTGG-3' complex: drug interaction with tandem G.T mismatches and hairpin loop backbone.

Binding of actinomycin D (ActD) to the seemingly single-stranded DNA (ssDNA) oligomer 5'-CCGTT3 GTGG-3' has been studied in solution using high-resolution nuclear magnetic resonance (NMR) techniques. A strong binding constant (8 x 10(6) M(-1)) and high quality NMR spectra have allowed us to determine the initial DNA structure using distance geometry as well as the final ActD-5'-CCGTT3 GTGG-3' complex structure using constrained molecular dynamics calculations. The DNA oligomer 5'-CCGTT3GTGG-3' in the complex forms a hairpin structure with tandem G.