One-pot Two-step Process Research Articles

Cobalt-catalyzed selective dehydrocoupling polymerization of prochiral silanes and diols

As a kind of material possessing thermal stability, biocompatibility and degradability, polysilylethers (PSEs) have potential applications. Different catalytic systems have been developed for the synthesis of PSEs. However, the resulted PSEs have similar structure, which is unfavorable for adjusting its properties. We herein synthesized a series of novel PSEs with pendant SiH groups via cobalt-catalyzed selective dehydrocoupling polymerization. Various diols and prochiral silanes are suitable for this method. This novel PSEs could also be obtained via a Co-catalyzed one-pot two-step process. Furthermore, asymmetric dehydrocoupling polymerization was studied and high-Mn PSE was obtained. After the cleavage of PSE by methyl magnesium iodide, chiral silane was obtained with high yield and moderate enantioselectivity.

In-Situ Growth and Immobilization of CdS Nanoparticles onto Functionalized MoS2 : Preparation, Characterization and Fabrication of Photoelectrochemical Cells.

A facile strategy for the controllable growth of CdS nanoparticles at the periphery of MoS2 en route the preparation of electron donor-acceptor nanoensembles is developed. Precisely, the carboxylic group of α-lipoic acid, as addend of the modified MoS2 obtained upon 1,2-dithiolane functionalization, was employed as anchor site for the in situ preparation and immobilization of the CdS nanoparticles in an one-pot two-step process. The newly prepared MoS2 /CdS hybrid material was characterized by complementary spectroscopic, thermal and microscopy imaging means. Absorption spectroscopy was employed to register the formation of MoS2 /CdS, by observing a broad shoulder centered at 420 nm due to CdS nanoparticles, while the excitonic bands of MoS2 were also evident. Moreover, based on the efficient quenching of the characteristic fluorescence emission of CdS at 725 nm by the presence of MoS2 , strong electronic interactions at the excited state between the two species within the ensemble were identified. Photoelectrochemical assays of MoS2 /CdS thin-film electrodes revealed a prompt, steady and reproducible anodic photoresponse during repeated on-off cycles of illumination. A significant zero-current photopotential of -540 mV and an anodic photocurrent of 1 μA were observed, underlining improved charge-separation and electron transport from CdS to MoS2 . The superior performance of the charge-transfer processes in MoS2 /CdS is of direct interest for the fabrication of photoelectrochemical and optoelectronic devices.

Preparation of a mimetic and degradable poly(ethylene glycol) by a non-eutectic mixture of organocatalysts (NEMO) via a one-pot two-step process.

A one-pot, two-step method for the preparation of degradable PEG is here presented. The full process addresses the requirements imposed by green chemistry and involves the use of a single and nontoxic non-eutectic mixture of organocatalysts. The strategy relies on the polycondensation of PEG800 after its functionalization by bio-derived 5-membered γ-butyrolactone.

Chemo-Enzymatic Synthesis of Poly(4-piperidine lactone- b-ω-pentadecalactone) Block Copolymers as Biomaterials with Antibacterial Properties.

With increasing troubles in bacterial contamination and antibiotic-resistance, new materials possessing both biocompatibility and antimicrobial efficacy are supposed to be developed for future biomedical application. Herein, we demonstrated a chemo-enzymatic ring opening polymerization (ROP) approach for block copolyester, that is, poly(4-benzyl formate piperidine lactone- b-ω-pentadecalactone) (PNPIL- b-PPDL), in a one-pot two-step process. Afterward, cationic poly(4-piperidine lactone- b-ω-pentadecalactone) (PPIL- b-PPDL) with pendent secondary amino groups was obtained via acidic hydrolysis of PNPIL- b-PPDL. The resulting cationic block copolyester exhibited high antibacterial activity against Gram negative E. coli and Gram positive S. aureus, while showed low toxicity toward NIH-3T3 cells. Moreover, the antibacterial property, cytotoxicity and degradation behavior could be tuned simply by variation of PPIL content. Therefore, we anticipate that such cationic block copolymers could potentially be applied as biomaterials for medicine or implants.

Facile synthesis of perfluoroalkylated fluorenes via a one-pot two-step three-component process

The efficient synthesis of perfluoroalkyl-substituted fluorenes directly from indenones, malononitrile and methyl perfluoroalk-2-ynoates via a one-pot two-step three-component cascade process is reported. Up to 12 examples of indenones with various substituents were converted into their corresponding functionalized fluorene derivatives in good to excellent yields.

One-pot two-step synthesis of 3-iodo-4-aryloxy coumarins and their Pd/C-catalyzed annulation to coumestans.

An efficient protocol for the synthesis of various coumestans from the intramolecular annulation of 3-iodo-4-aryloxy coumarins through C–H activation has been developed. When 3-iodo-4-aryloxy coumarins were treated with 10% Pd/C (0.3 mol% Pd) in the presence of sodium acetate, the corresponding coumestans were produced in good to excellent yield. Reusability of the palladium catalyst was investigated in up to three consecutive cycles and it was found that the yield of the reaction was almost unaltered. Sequential iodination and O-arylation of 4-hydroxy coumarins leading to the 3-iodo-4-aryloxy coumarins were also achieved in a one-pot two-step process starting from aryl iodides in high yield. Pivalic acid was revealed to be the most effective additive for the later method to produce 3-iodo-4-phenoxy coumarins. Different functional groups bearing electron-donating as well as withdrawing groups are also tolerant to the reaction conditions.

Green One-pot Synthesis of Novel Polysubstituted Pyrazole Derivatives as Potential Antimicrobial Agents.

Various biological properties of natural and synthetic pyrazole derivatives such as anti-inflammatory, antimicrobial, neuroprotective, anticonvulsant, antidepressant and anticancer activities encouraged us to propose a new, fast, green and eco-friendly procedure for the preparation of some novel 5-amino-3-(aryl substituted)-1-(2,4-dinitrophenyl)-1H-pyrazole-4-carbonitriles. They were efficiently synthesized via one-pot two-step process reaction of malononitrile, 2,4-dinitrophenylhydrazine and different benzaldehydes in deep eutectic solvent (DES) glycerol/potassium carbonate. The products yield and reaction times were considerably improved in the presence of applied DES. Antibacterial effects of all newly synthesized pyrazoles in comparison with several common antibiotics were evaluated against a variety of Gram-positive and Gram-negative pathogenic bacteria. In addition to, their inhibitory activities on three fungi were compared to some current antifungal agents. The moderate to good antimicrobial potentials particularly against fungi were observed in the major heterocyclic compounds according to the IZD, MIC, MBC and MFC results.

Chemo-biocatalytic one-pot two-step conversion of cyclic amine to lactam using whole cell monoamine oxidase

BACKGROUND Most biocatalysts currently involved in one-pot chemoenzymatic cascades are pure enzymes, while whole cells and crude enzyme extracts remain unexplored. This work aims to develop a chemo-biocatalytic one-pot two-step system involving whole cell monoamine oxidase (MAO, EC 1.4.3.4) coupled with a Cu-based oxidative system (CuI/H2O2) for the transformation of 1,2,3,4-tetrahydroisoquinoline (THIQ) to 3,4-dihydroisoquinolin-1(2H)-one (DHIO). RESULTS MAO-N variants D9 and D11 were tested as whole cell and crude lysate biocatalysts for biological oxidation. Whole Escherichia coli OverExpress C43(DE3) cells expressing MAO-N D9 showed the best performance (Vmax = 36.58 mmol L−1 h−1, KM = 8.124 mmol L−1, maximum specific productivity 89.3 μmol min−1 g−1DCW) and were employed in combination with CuI/H2O2 in a sequential one-pot two-step process. The biotransformation was scaled-up to the initial volume of 25 mL and after triple THIQ feeding, 48.2 mmol L−1 of the intermediate 3,4-dihydroisoquinoline (DHIQ) was obtained with a yield of 71.3%. Afterwards, chemical catalysts (1 mol% CuI and 10 eq. H2O2) were added to the biologically produced DHIQ, which was transformed to ∼30 mmol L−1 DHIO at 69.4% overall yield. CONCLUSION As MAO-N variants have wide substrate specificity, this work broadens the portfolio of one-pot chemoenzymatic processes employing whole cell biocatalysts, representing an alternative to using pure enzymes. © 2016 Society of Chemical Industry

Cascade reaction of propargylic alcohols with hydroxylamine hydrochloride: facile synthesis of α,β-unsaturated oximes and nitriles

We have developed an easy and practical method for the synthesis of α,β-unsaturated oximes and nitriles from readily available propargylic alcohols with hydroxylamine hydrochloride (NH2OH·HCl) under metal-free conditions. By using or not using p-toluenesulfonyl chloride (p-TsCl) as the dehydrating promoter, the desired nitriles or oximes could be obtained, respectively via a three-step one-pot or two-step one-pot process in moderate to excellent yields with good functional group compatibility.

One-pot two-step process for direct propylene oxide production catalyzed by bi-functional Pd(Au)@TS-1 materials

Different bi-functional materials (Pd(Au)@TS-1) based on metallic nanoparticles supported onto active nanocrystalline titanium silicalite (TS-1) zeolites were synthesized, characterized and used as recyclable heterogeneous catalysts for direct propylene oxide production from hydrogen, oxygen and propylene through one-pot two-step consecutive process. These catalysts allowed carrying out the combined reaction where metallic nanoparticles catalyzed the formation of in situ H2O2 that was the necessary intermediate for propylene epoxidation catalyzed by active TS-1 nanocrystalline support. Several variables were considered such as use of supercritical CO2 conditions, modifiable content of metallic species, and presence of additional co-solvents, surface acidity inhibitors and H2O2 stabilizers. Reusability and stability of the bi-functional catalyst was showed through consecutive catalytic cycles.

An Efficient One-Pot Two-Step Three-Component Process for the Synthesis of Trifluoromethylated Hydrochromenes

A one-pot two-step three-component process for the synthesis of trifluoromethylated 2-hydroxy-5-oxo-3,4,5,6,7,8-hexahydro-2H-chromenes has been developed. The three-component reaction of dimedone, substituted benzaldehydes, and methyl 4,4,4-trifluorobut-2-ynoate gave the desired products in moderate to good yields. Excellent regioselectivity and diastereoselectivity were observed. Furthermore, refluxing the product chromenes with p-toluenesulfonic acid in toluene gave the corresponding dehydrated products – trifluoromethylated 5-oxo-5,6,7,8-tetrahydro-4H-chromenes.

ChemInform Abstract: Synthesis of 8‐Aminoquinolines by Using Carbamate Reagents: Facile Installation and Deprotection of Practical Amidating Groups.

Described herein is the development of practical routes to 8-aminoquinolines by using readily installable and easily deprotectable amidating reagents. Two scalable procedures were optimized under Rh(III) -catalyzed conditions: i) the use of pre-generated chlorocarbamates and ii) a two-step one-pot process that directly employs carbamates. Both approaches are highly convenient for the gram-scale synthesis of 8-aminoquinolines under mild conditions. Facile deprotection of the synthetically versatile amidating groups was achieved under the Pd-catalyzed transfer hydrogenation conditions with simultaneous deoxygenation of quinoline N-oxides, thus yielding 8-aminoquinolines in excellent overall efficiency.

Regularly grafted polymer brush with degradable PCL backbone by ring-opening polymerization and “click” reaction: synthesis and self-assembly

A series of polymer brushes with degradable poly(caprolactone) (PCL) backbones were synthesized via “grafting onto” approach by combination of the ring-opening polymerization (ROP) and “click” reaction. First, P(αClCL) was synthesized by ROP and then the chloride was substituted by azide group to obtain P(N3CL) backbone; then polymer brushes were synthesized by “click” reaction of alkynyl-PCL (ay-PCL) and alkynyl-PEO (ay-PEO) onto P(N3CL). The products were characterized by gel permeation chromatography (GPC), FT-IR and 1H NMR. Results indicated that the ay-PCL can be grafted onto P(N3CL) backbone quantitatively at 1 : 1 ratio of alkynyl group to azide group and the branch was attached onto each repeating unit because of lower steric resistance and graft density. Also the amphiphilic polymer brushes with various hetero-branches of PEO/PCL ratios were synthesized by one-pot two-step process. The amphiphilic polymer brushes self-assembled into micelles with various PEO/PCL ratios and have potential application in drug loading and delivery.

Potential Application of Oleylamine-encapsulated AgInS2-ZnS Quantum Dots for Cancer Cell Labeling

This study improves a simple strategy for phase transfer process via ultrasonication approach. Water-soluble AgInS2-ZnS quantum dots (QDs) encapsulated with oleylamine have been successfully prepared without the presence of surfactant or polymer. During the propagation process, ultrasonication creates harmonic pressure (relative to the equilibrium hydrostatic pressure of the liquid), which was helpful for the dispersion of nanomaterials in two immiscible phases. The highly photoluminescent ZnS coated AgInS2 QDs (up to 55.3% QY) was synthesized with a one-pot two-step process with narrow particle distribution and successfully transferred to water phase without significant effect on optical properties. Beside QDs characterization, some factors such as pH stability, ionic strength, and bonding properties were investigated to reach a good condition of water soluble AgInS2-ZnS QDs. These nanoparticles also showed potential application for cancer cell staining. To demonstrate the targeting capability, folic acid was further conjugated with oleylamine encapsulated AgInS2-ZnS QDs for HeLa and MCF7 cancer cell staining. This study also reveals that the water-soluble QDs still gave lower fluorescence intensity on confocal imaging, even without folic acid conjugation. Moreover, folic acid is efficiently internalized into cells through folate receptor-mediated endocytosis. Confocal imaging characterization further informs folic acid-conjugated AgInS2-ZnS QDs that could specifically be targeted to the human cervical (HeLa) cells.

Synthesis of 8-Aminoquinolines by Using Carbamate Reagents: Facile Installation and Deprotection of Practical Amidating Groups.

Described herein is the development of practical routes to 8-aminoquinolines by using readily installable and easily deprotectable amidating reagents. Two scalable procedures were optimized under Rh(III) -catalyzed conditions: i) the use of pre-generated chlorocarbamates and ii) a two-step one-pot process that directly employs carbamates. Both approaches are highly convenient for the gram-scale synthesis of 8-aminoquinolines under mild conditions. Facile deprotection of the synthetically versatile amidating groups was achieved under the Pd-catalyzed transfer hydrogenation conditions with simultaneous deoxygenation of quinoline N-oxides, thus yielding 8-aminoquinolines in excellent overall efficiency.

Direct synthesis of propylene carbonate from propylene and carbon dioxide catalyzed by quaternary ammonium heteropolyphosphatotungstate–TBAB system

In this paper, we have developed a highly efficient method for the direct preparation of propylene carbonate from propylene and carbon dioxide (CO2) using quaternary ammonium heteropolyphosphatotungstate–quaternary ammonium halide catalytic system with anhydrous hydrogen peroxide as an oxidant through one-pot two-step process. The effects of the amount of tetrabutylammonium bromide (TBAB), the concentration of hydrogen peroxide and other reaction conditions were investigated. The catalyst system gave an optimum propylene oxide yield (91%) at 75 °C in oxidation step and the highest propylene carbonate yield (99%) at 140 °C and 3.0 MPa in cycloaddition step. Based on the results, a reaction mechanism has been proposed.

ChemInform Abstract: Four‐Component, One‐Pot Synthesis of N‐Alkyl‐4‐oxo‐3‐phenylhexahydro‐4H‐spiro{[1,3]dioxolo[4′,5′:4,5]furo [2,3‐f][1,2,3]triazolo[1,5‐a] [1,4]diazepine‐9,1′‐cyclohexane}‐6‐carboxamide Derivatives.

A four-component, six-center Ugi reaction of sugar azidoaldehyde, benzylamine, alkyl isocyanide, and phenylpropiolic acid has been developed to produce a novel class of hexahydro-4 H -spiro{[1,3]dioxolo[4′,5′:4,5]furo[2,3- f ][1,2,3]triazolo[1,5- a ][1,4]di­azepine-9,1′-cyclohexane}-6-carboxamide derivatives in good yields with high selectivity. It is a one-pot two-step process affording sugar-derived triazolodiazepines starting from simple precursors. The stereochemistry of the products was confirmed by NMR and NOE studies.

Novel one-pot process for the synthesis of ethyl 2-imino-4-methyl-2,3-dihydrothiazole-5-carboxylates

A facile one-pot two-step process for the synthesis of ethyl 2-imino-4-methyl-2,3-dihydrothiazole-5-carboxylates via the cyclocondensation of ethyl 2-thiocyanatoacetoacetate with a variety of hydrazine and hydrazide derivatives has been developed. Ethyl 2-thiocyanatoacetoacetate itself has been synthesized as intermediate from the reaction of ethyl 2-chloroacetoacetate with potassium thiocyanate (KSCN). The molecular structures of these newly synthesized compounds were elucidated on the basis of elemental analysis and spectral data.

An efficient one-pot two-step three-component process for the synthesis of perfluoroalkylated biphenyls

A practical and economical process for the synthesis of perfluoroalkylated biphenyl derivatives has been developed. The three-component reaction of aromatic ketones, malononitrile and methyl perfluoroalk-2-ynoates gave the desired products in good to excellent yields via a one-pot two-step process.

Four-Component, One-Pot Synthesis of N-Alkyl-4-oxo-3-phenylhexahydro-4H-spiro{[1,3]dioxolo[4′,5′:4,5]furo[2,3-f][1,2,3]triazolo[1,5-a][1,4]diazepine-9,1′-cyclohexane}-6-carboxamide Derivatives

A four-component, six-center Ugi reaction of sugar azidoaldehyde, benzylamine, alkyl isocyanide, and phenylpropiolic acid has been developed to produce a novel class of hexahydro-4 H -spiro{[1,3]dioxolo[4′,5′:4,5]furo[2,3- f ][1,2,3]triazolo[1,5- a ][1,4]di­azepine-9,1′-cyclohexane}-6-carboxamide derivatives in good yields with high selectivity. It is a one-pot two-step process affording sugar-derived triazolodiazepines starting from simple precursors. The stereochemistry of the products was confirmed by NMR and NOE studies.