Luke R. Odell

Inhibition of dynamin mediated endocytosis by the dynoles: synthesis and functional activity of a family of indoles

Screening identified two bisindolylmaleimides as 100 microM inhibitors of the GTPase activity of dynamin I. Focused library approaches allowed development of indole-based dynamin inhibitors called dynoles. 100-Fold in vitro enhancement of potency was noted with the best inhibitor, 2-cyano-3-(1-(2-(dimethylamino)ethyl)-1H-indol-3-yl)-N-octylacrylamide (dynole 34-2), a 1.3 +/- 0.3 microM dynamin I inhibitor. Dynole 34-2 potently inhibited receptor mediated endocytosis (RME) internalization of Texas red-transferrin. The rank order of potency for a variety of dynole analogues on RME in U2OS cells matched their rank order for dynamin inhibition, suggesting that the mechanism of inhibition is via dynamin. Dynoles are the most active dynamin I inhibitors reported for in vitro or RME evaluations. Dynole 34-2 is 15-fold more active than dynasore against dynamin I and 6-fold more active against dynamin mediated RME (IC(50) approximately 15 microM; RME IC(50) approximately 80 microM). The dynoles represent a new series of tools to better probe endocytosis and dynamin-mediated trafficking events in a variety of cells.

Aminocarbonylations Employing Mo(CO)6 and a Bridged Two-Vial System: Allowing the Use of Nitro Group Substituted Aryl Iodides and Aryl Bromides

A bridged two-vial system aminocarbonylation protocol where Mo(CO)(6) functions as an external in situ solid source of CO has been developed. For the first time both nitro group containing aryl/heteroaryl iodides and bromides gave good to excellent yields in the Mo(CO)(6)-mediated and palladium(0)-catalyzed conversion to benzamides, while the identical one-vessel protocol afforded extensive reduction of the nitro functionality. The above-mentioned bridged two-compartment protocol furnished good results with both primary amines and secondary amines and sluggish aniline nucleophiles at 65-85 °C reaction temperatures.

Functionalized 3-amino-imidazo[1,2-a]pyridines: A novel class of drug-like Mycobacterium tuberculosis glutamine synthetase inhibitors

3-Amino-imidazo[1,2-a]pyridines have been identified as a novel class of Mycobacterium tuberculosis glutamine synthetase inhibitors. Moreover, these compounds represent the first drug-like inhibitors of this enzyme. A series of compounds exploring structural diversity in the pyridine and phenyl rings have been synthesized and biologically evaluated. Compound 4n was found to be the most potent inhibitor (IC(50)=0.38+/-0.02 microM). This compound was significantly more potent than the known inhibitors, l-methionine-SR-sulfoximine and phosphinothricin.

Microwave-Assisted Synthesis of Weinreb and MAP Aryl Amides via Pd-Catalyzed Heck Aminocarbonylation Using Mo(CO)6 or W(CO)6

A simple and expedient process for the Heck aminocarbonylative synthesis of Weinreb and MAP amide acylating agents, from aryl halides, is reported. This methodology utilizes solid sources of CO making it readily accessible to chemists working in small-scale laboratory applications.

Trisubstituted Imidazoles as Mycobacterium tuberculosis Glutamine Synthetase Inhibitors

Mycobacterium tuberculosis glutamine synthetase (MtGS) is a promising target for antituberculosis drug discovery. In a recent high-throughput screening study we identified several classes of MtGS inhibitors targeting the ATP-binding site. We now explore one of these classes, the 2-tert-butyl-4,5-diarylimidazoles, and present the design, synthesis, and X-ray crystallographic studies leading to the identification of MtGS inhibitors with submicromolar IC50 values and promising antituberculosis MIC values.

Microwave-assisted synthesis of small molecules targeting the infectious diseases tuberculosis, HIV/AIDS, malaria and hepatitis C

The unique properties of microwave in situ heating offer unparalleled opportunities for medicinal chemists to speed up lead optimisation processes in early drug discovery. The technology is ideal for small-scale discovery chemistry because it allows full reaction control, short reaction times, high safety and rapid feedback. To illustrate these advantages, we herein describe applications and approaches in the synthesis of small molecules to combat four of the most prevalent infectious diseases; tuberculosis, HIV/AIDS, malaria and hepatitis C, using dedicated microwave instrumentation.

Azido and diazarinyl analogues of bis-tyrphostin as asymmetrical inhibitors of dynamin GTPase

Probing the dynamin binding site: Bis‐tyrphostin (1, Bis‐T), is a potent inhibitor of the phospholipid‐stimulated GTPase activity of dynamin I. Analogues of Bis‐T have significant potential as a biological probes for the dissection of endocytic pathways. Bis‐T‐derived compounds were synthesised and evaluated for their ability to inhibit the GTPase activity of dynamin I. Two analogues (23 and 24) represent the first asymmetrically substituted Bis‐T analogues to retain dynamin inhibition.

Evaluation of the amino acid binding site of Mycobacterium tuberculosis glutamine synthetase for drug discovery

A combination of a literature survey, structure-based virtual screening and synthesis of a small library was performed to identify hits to the potential antimycobacterial drug target, glutamine synthetase. The best inhibitor identified from the literature survey was (2S,5R)-2,6-diamino-5-hydroxyhexanoic acid (4, IC(50) of 610+/-15microM). In the virtual screening 46,400 compounds were docked and subjected to a pharmacophore search. Of these compounds, 29 were purchased and tested in a biological assay, allowing three novel inhibitors containing an aromatic scaffold to be identified. Based on one of the hits from the virtual screening a small library of 15 analogues was synthesized producing four compounds that inhibited glutamine synthetase.

Transmetallation Versus β-Hydride Elimination : The Role of 1,4 Benzoquinone in Chelation-Controlled Arylation Reactions with Arylboronic Acids

AbstractThe formation of an atypical, saturated, diarylated, Heck/Suzuki, domino product produced under oxidative Heck reaction conditions, employing arylboronic acids and a chelating vinyl ether, has been investigated by DFT calculations. The calculations highlight the crucial role of 1,4-benzoquinone (BQ) in the reaction. In addition to its role as an oxidant of palladium, which is necessary to complete the catalytic cycle, this electron-deficient alkene opens up a low-energy reaction pathway from the post-insertion σ-alkyl complex. The association of BQ lowers the free-energy barrier for transmetallation of the σ-alkyl complex to create a pathway that is energetically lower than the oxidative Heck reaction pathway. Furthermore, the calculations showed that the reaction is made viable by BQ-mediated reductive elimination and leads to the saturated diarylated product.

Synthesis of 4-Quinolones via a Carbonylative Sonogashira Cross-Coupling Using Molybdenum Hexacarbonyl as a CO Source

A palladium-catalyzed CO gas-free carbonylative Sonogashira/cyclization sequence for the preparation of functionalized 4-quinolones from 2-iodoanilines and alkynes via two different protocols is described. The first method (A) yields the cyclized products after only 20 min of microwave (MW) heating at 120 °C. The second method (B) is a gas-free one-pot two-step sequence which runs at room temperature, allowing the use of sensitive substituents (e.g., nitro and bromide groups). For both protocols, molybdenum hexacarbonyl was used as a solid source of CO.