Search

A highly efficient method for C-F bond functionalization of a broad variety of activated and unactivated aliphatic substrates with inexpensive lithium iodide is presented. Primary, secondary, tertiary, benzylic, propargylic and α-functionalized alkyl fluorides react in chlorinated or aromatic solvents at room temperature or upon heating to the corresponding iodides which are isolated in 91-99% yield. The reaction is selective for aliphatic monofluorides and can be coupled with

Cross-coupling of alkyl fluorides and organocuprates is accomplished via aluminum halide mediated C-F bond activation and subsequent C

A highly efficient method for C–F bond functionalization of a broad variety of activated and unactivated aliphatic substrates with inexpensive lithium iodide is presented. Primary, secondary, tertiary, benzylic, propargylic and α-functionalized alkyl fluorides react in chlorinated or aromatic solvents at room temperature or upon heating to give the corresponding iodides, which are isolated in 91–99% yield. The reaction is selective for aliphatic monofluorides and can be coupled with in situ nucleophilic iodide replacements to install carbon–carbon, carbon–nitrogen, and carbon–sulfur bonds with high yields. Alkyl difluorides, trifluorides, even in activated benzylic positions, are inert under the same conditions and aryl fluoride bonds are also tolerated.

Suzuki cross-coupling of benzylic and unactivated aliphatic fluorides with aryl- and alkenylboronic acids has been achieved via mechanistically distinct Pd and Ni catalyzed pathways that outperform competing protodeboronation, β-hydride elimination and homocoupling processes. The utility is demonstrated with more than twenty examples including heterocyclic structures, 1,1-disubstituted and trans-1,2-disubstituted alkenes, and by the incorporation of acetonitrile into functionalized (hetero)arenes.

Ubiquitin-Specific Protease-13 (USP13) promotes protein de-ubiquitination. USP13 levels are upregulated in post-mortem Parkinson’s disease, whereas USP13 knockdown via shRNA reduces alpha-synuclein levels in animal models. We studied the role of USP13 in knockout mice expressing lentiviral human alpha-synuclein and investigated the impact of a small molecule inhibitor of USP13, BK50118-C, on alpha-synuclein pathology and animal behavior. Alpha-synuclein was expressed unilaterally in substantia nigra (SN) of USP13 deficient mice that were treated with a daily intraperitoneal injection of 100 mg/kg BK50118-C or DMSO for four consecutive weeks, and behavioral and functional assays were performed. Wild-type USP13+/+ mice expressing lentiviral human alpha-synuclein showed motor and behavioral defects that were not seen in partially (USP13+/−) or completely (USP13−/−) deficient USP13 mice. BK50118-C displayed a wide and favorable therapeutic dose range in vivo. Treatment with BK50118-C significantly reduced ubiquitinated alpha-synuclein, increased dopamine levels, and improved motor and behavioral symptoms in wild-type (USP13+/+), but not USP13 deficient, mice. These data suggest that USP13 is critical to the neuropathology of alpha-synuclein, whereas a novel small molecule inhibitor of USP13 is a potential therapeutic agent of alpha-synucleinopathies.

Analytical methods that allow simultaneous determination of the concentration and enantiomeric composition of small sample amounts and are also compatible with high-throughput multi-well plate technology have received increasing attention in recent years. We now introduce a new class of broadly useful small-molecule probes and a relay sensing strategy that together accomplish these tasks with five classes of compounds including the challenging group of mono-alcohols-a scope that stands out among previously reported UV, fluorescence, and CD assays. Several chlorophosphite probes and aniline indicators have been evaluated and used for on-the-fly CD/UV sensing following a continuous workflow. The wide application range of the readily available sensors is highlighted with almost 30 alcohols, diols, hydroxy acids, amines and amino alcohols, and the accuracy of the stereochemical analysis is showcased with samples covering a wide range of concentrations and enantiomeric ratios.

The role of Discoidin Domain Receptors (DDRs) is poorly understood in neurodegeneration. DDRs are upregulated in Alzheimer’s and Parkinson’s disease (PD), and DDRs knockdown reduces neurotoxic protein levels. Here we show that potent and preferential DDR1 inhibitors reduce neurotoxic protein levels in vitro and in vivo. Partial or complete deletion or inhibition of DDR1 in a mouse model challenged with α-synuclein increases autophagy and reduces inflammation and neurotoxic proteins. Significant changes of cerebrospinal fluid microRNAs that control inflammation, neuronal injury, autophagy and vesicular transport genes are observed in PD with and without dementia and Lewy body dementia, but these changes are attenuated or reversed after treatment with the DDR1 inhibitor, nilotinib. Collectively, these data demonstrate that DDR1 regulates autophagy and reduces neurotoxic proteins and inflammation and is a therapeutic target in neurodegeneration.

A generally useful palladium-catalyzed method for the asymmetric allylic amination with a large variety of isatins, sulfonamides, imides, amines, and N-heterocycles is introduced. A single protocol...

The widespread use of fluorinated organic compounds in the health, agrochemical, and materials sciences is sustained by a steadily growing pool of commercially available fine chemicals. The synthetic utility of the increasingly ubiquitous Csp

The widespread use of fluorinated organic compounds in the health, agrochemical, and materials sciences is sustained by a steadily growing pool of commercially available fine chemicals. The synthetic utility of the increasingly ubiquitous Csp 3 ─F bond, however, remains to be fully exploited, which is often a difficult task because of its paramount stability and chemical inertness. Here, we demonstrate chemodivergent activation of monofluoroalkyl compounds toward either nucleophilic or electrophilic intermediates. This is accomplished under conditions that are compatible with several reaction types and many functional groups, which drastically widens the current scope of organofluorine chemistry and sets the stage for carbon-carbon and carbon-heteroatom bond formations, stereoselective construction of bisoxindole alkaloid scaffolds via in situ Umpolung, and cross-electrophilic coupling methodology. The selective generation of either nucleophilic or electrophilic species and the possibility of doing so simultaneously or, alternatively, switching molecular polarity enable previously unidentified synthetic opportunities that recognize alkyl fluorides as chemodivergent building blocks.

Asymmetric reaction development within a day or two has been a dream of synthetic chemists for several decades. We now show that such a task is feasible with a highly efficient streamlined screening strategy using the asymmetric allylation of isatins with a chiral boron complex as a case study. Our high-throughput screening (HTS) method is based on fast optical UV/CD analysis of minute amounts of crude reaction mixtures (≈3 mg scale) and it obviates product isolation and the general need for reference compounds which greatly reduces preliminary work and analysis time. The setup, reaction screening, analysis and data processing for 54 asymmetric allylations of nine different isatins in six different solvents was handled by a single operator in less than 20 work hours. One could easily extend this HTS strategy to hundreds of reactions in roughly the same time frame and further reduce the labor with commercially available automated high-throughput experimentation equipment. The effectiveness of this asymmetric reaction development strategy is confirmed with the upscale synthesis of two representative 3-allyl-3-hydroxyisatins in 98-99 % yield and with 91-94 % ee under optimized conditions.

A generally useful palladium catalyzed method for the asymmetric allylic amination with a large variety of isatins, sulfonamides, imides, amines and N-heterocycles is introduced. A single protocol with a readily available catalyst accomplishes this reaction at room temperature with high yields and enantioselectivities often exceeding 90% which is demonstrated with thirty-one examples.

A highly diastereoselective organocatalytic reaction for the synthesis of fluorinated 3,3'-bisindolines exhibiting adjacent tetrasubstituted carbon stereocenters is described. A broad variety of heterochiral bisindolines was prepared in 91-99% yield using 3-fluorooxindoles and isatylidene malononitriles in the presence of catalytic amounts of triethylamine in water or aqueous solution. The reaction can be upscaled without compromising yield and diastereoselectivity and the general usefulness of this method was demonstrated with various Michael acceptors and extended to aldol and Mannich reactions.

An efficient organocatalytic method for the synthesis of difluoromethyl and trifluoromethyl substituted β-hydroxynitriles is introduced. The decarboxylative cyanomethylation of fluorinated ketones with readily available cyanoacetic acid gives a variety of tertiary alcohols in high yields and without concomitant water elimination. The reaction occurs in the presence of catalytic amounts of triethylamine, can be upscaled and applied to chlorofluoromethyl ketones and difluoromethyl ketimines.

Synthetisch vielseitige 3,3-disubstituierte Fluoroxindole mit benachbarten Chiralitatszentren wurden in hohen Ausbeuten und mit exzellenten Enantio-, Diastereo- und Regioselektivitaten durch katalytische asymmetrische Alkylierung von Fluorenolaten mit Allylacetaten erhalten. Die Reaktion verlauft unter milden Bedingungen und kann in groseren Ansatzen ohne Beeintrachtigung der asymmetrischen Induktion durchgefuhrt werden. Der praparative Nutzen der Produkte wird durch den Einbau von zusatzlichen Funktionsgruppen und die Bildung von C3-fluorierten Oxindolen mit vier angrenzenden Chiralitatszentren belegt. Eine neue Methode zur C-F-Bindungsfunktionalisierung, die neuartige Moglichkeiten fur die stereoselektive Erzeugung eines chiralen quartaren Kohlenstoffzentrums im Alkaloidgerust ermoglicht, wird aufgezeigt.

A highly diastereoselective organocatalytic method that produces 3-fluoro-3'-hydroxy-3,3'-bisoxindoles and the corresponding 3-fluoro-3'-amino derivatives having two adjacent chirality centers from fluorooxindoles and isatins in high yields is described. The reaction occurs in protic solvents at room temperature, it can be upscaled without compromising yield and stereoselectivity, and chromatographic product purification is not required.

Leishmaniases are a complex of tropical and sub-tropical diseases caused by parasites of the genus Leishmania and transmitted by the bite of an insect vector, the sandfly. Quinolines of natural origin have shown interesting antileishmanial activities on several experimental leishmaniasis models. A classical daily treament with 2-n-propylquinoline (2-n-PQ) on five consecutive days in mice model is not sufficient to cure the mice infected with Leishmania donovani and the activity requires a 10-day treatment duration whatever the route (oral, parenteral) because of a short half-life elimination of the drug. Therefore, 2-n-PQ derivatives were bound to soluble polysaccharides to improve their solubility, delay their elimination half-life and therefore enhance the activity. In vitro release at 37oC in phosphate buffer was performed in various conditions and showed that around 65% of the compound was released in 24 h. In vitro, the most active conjugate was the dextran-2PQA conjugate exhibiting an IC50 value at 12 µg/mL on Leishmania donovani intramacrophage amastigotes. However, this system did not allow a sufficient release of the active principle explaining the lack of in vivo activity. Another approach consisted in administering 2-n-PQ intravenously. Two systems were successful both in vitro and in vivo : a liposomal formulation named 2-n-PQ-LIP and a hydroxypropyl beta-cyclodextrin inclusion complex designated as 2-n-PQ-HPC. The most interesting one was the liposomal formulation, active on the L. donovani Balb/c mouse model, by reducing the parasite burden by more than 80% after an intravenous treatment regimen of 3 mg equivalent 2-n-PQ/kg/day given on five consecutive days. No synergistic activity between 2-n-PQ and Amphotericin B was monitored either in vitro or in vivo. These formulations should be studied further on other leishmaniasis models and for toxicological considerations. Acknowledgements This work was supported by a grant from the Indo-French Centre of Advanced Research, New Delhi (CEFIPRA) (No. 4803-04) and Kaluvu Balaraman was recipient of a CEFIPRA postdoctoral fellowship.

Enantioselective fluorination of aliphatic cyclic and acyclic β-ketoesters was achieved in excellent yield (up to 98%) with moderate to good enantioselectivities (up to 86% ee) using tartrate derived bidentate bioxazoline-Cu(II) complexes. This is the first report of a bioxazoline which forms a 5-membered chelate inducing enantioselectivity in the asymmetric fluorination of β-ketoesters.

A series of highly efficient and inexpensive bioxazoline ligands were easily synthesized from tartaric acid and further explored for enantioselective addition of terminal alkynes to imines in combination with copper(II) salts. This is the first ever report showing application of bidentate bioxazoline ligands in the synthesis of propargylamines with good enantioselectivity.

A new class of highly stable O,N,N,O-tetradentate bioxazoline ligands were synthesized from l-tartaric acid. Exploration of those ligands in Pd-catalyzed asymmetric allylic alkylation yielded alkylated product up to 96% ee. Necessity of additional chelation to obtain high enantioselectivity was also demonstrated. Structural modifications of this ligand might result in identification of a novel privileged chiral ligand from an inexpensive chiral pool. � 2013 Elsevier Ltd. All rights reserved.

Sequential chlorination/fluorination of aromatic trifluoroacetylated ketones gives 1-aryl 2-chloro-2,4,4,4-tetrafluorobutan-1,3-dione hydrates that are used for the synthesis of ketones and alkenes exhibiting a terminal bromochlorofluoromethyl group. The hydrates undergo detrifluoroacetylative cleavage and subsequent bromination in the presence of a copper(II) bisoxazoline catalyst, K2CO3, and NBS at room temperature. The corresponding bromochlorofluoromethyl ketones can be applied in Wittig and Horner–Wadsworth–Emmons reactions and dibromoalkenylations.

Synthetically versatile 3,3-disubstituted fluorooxindoles exhibiting vicinal chirality centers were obtained in high yields and with excellent enantio-, diastereo-, and regioselectivity through catalytic asymmetric fluoroenolate alkylation with allylic acetates. The reaction proceeds under mild conditions and can be scaled up without compromising the asymmetric induction. The unique synthetic usefulness of the products is highlighted by the incorporation of additional functionalities and the formation of 3-fluorinated oxindoles exhibiting an array of four adjacent centers of chirality. A new C-F bond functionalization path that provides unprecedented possibilities for the stereoselective generation of a chiral quaternary carbon center in the alkaloid scaffold is introduced.

Sequential chlorination/fluorination of aromatic trifluoroacetylated ketones gives 1-aryl 2-chloro-2,4,4,4-tetrafluorobutan-1,3-dione hydrates that are used for the synthesis of ketones and alkenes exhibiting a terminal bromochlorofluoromethyl group. The hydrates undergo detrifluoroacetylative cleavage and subsequent bromination in the presence of a copper(II) bisoxazoline catalyst, K2CO3, and NBS at room temperature. The corresponding bromochlorofluoromethyl ketones can be applied in Wittig and Horner–Wadsworth–Emmons reactions and dibromoalkenylations.

Novel C 2-symmetric chiral bioxazolines were synthesized in good yields by the fusion of optically active acids with a tartaric acid derivative. Complexes of these products with copper(II) acetate monohydrate were found to be excellent catalysts for the Henry reaction, giving various nitro alcohols in very good yields and up to 84% enantiomeric excess. Although only five-membered chelation is possible with these ligands, they give better enantioselectivities than other bioxazoline ligands that undergo similar coordination. � Georg Thieme Verlag Stuttgart � New York.

Symmetrical 1,3-diynes were obtained in quantitative yields using the copper(II) acetate catalyzed homocoupling of terminal alkynes in the presence of a stoichiometric amount of piperidine at 25 �C under aerobic conditions. We also accomplished facile syntheses of unsymmetric 1,3-diynes by heterocoupling terminal alkynes in very good yields under the reported reaction conditions. � Georg Thieme Verlag Stuttgart.

2-n-propylquinoline (2-n-PQ) had shown interesting in vivo antileishmanial activities after administration by oral route on leishmaniasis animal models. However, the lipophilic properties of this compound avoid its use by intravenous route, this route being indicated in cases of severe visceral leishmaniasis with vomiting. Thus, a 2-n-propylquinoline hydroxypropyl beta-cyclodextrin (2-n-PQ-HPC) formulation was set up in this aim. The formulation was active in vitro both on Leishmania donovani axenic and intramacrophage amastigotes with IC50 values at 6.22±0.82μM and 20.01±0.52μM, respectively, without any toxicity on macrophages. 2-n-PQ-HPC exhibited similar activity on WT and drug-resistant parasites. Its in vitro interactions with antimonials, amphotericin B and miltefosine were found as additive both in axenic amastigotes and intramacrophage amastigotes. 2-n-PQ-HPC was not able to generate drug resistance after in vitro drug pressure since the resistance index was less than 4. 2-n-PQ-HPC was also active on the L. donovani/Balb/c mice model with an intravenous treatment regimen at 10mgkg(-1)day(-1) on 10 consecutive days without hepatic, renal and blood toxicity. The pharmacokinetics of 2-n-PQ in rats showed that after an intravenous treatment of the formulation at 10mgkg(-1), the plasma drug concentrations rapidly declined bi-exponentially with a half-life of 58.7min and a total clearance of 18.63lh(-1)kg(-1). The apparent volume of distribution was higher than the blood volume in rats, indicating that 2-n-PQ was well distributed in tissues, allowing parasite elimination. Such a formulation is worth of further antiparasitic and toxicological evaluations.

The bisoxazoline (BOX) is found to be an efficient ligand in Pd-catalyzed asymmetric allylic alkylation.

Tartaric acid derived bidentate bisoxazoline ligands are applied as catalysts for the NFSI promoted enantioselective fluorination of β-keto esters (I).

A new class of highly stable O,N,N,O-tetradentate bioxazoline ligands were synthesized from l-tartaric acid. Exploration of those ligands in Pd-catalyzed asymmetric allylic alkylation yielded alkylated product up to 96% ee. Necessity of additional chelation to obtain high enantioselectivity was also demonstrated. Structural modifications of this ligand might result in identification of a novel privileged chiral ligand from an inexpensive chiral pool.

A new class of bidentate bisoxazoline ligands is applied to the addition of alkynes to imines.

Novel C 2-symmetric chiral bioxazolines were synthesized in good yields by the fusion of optically active acids with a tartaric acid derivative. Complexes of these products with copper(II) acetate monohydrate were found to be excellent catalysts for the Henry reaction, giving various nitro alcohols in very good yields and up to 84% enantiomeric excess. Although only five-membered chelation is possible with these ligands, they give better enantioselectivities than other bioxazoline ligands that undergo similar coordination.