Nitrones are presently the most used spin traps to characterize free radicals in biological systems,[1-5] with Phenyl-N-tertiobutyl Nitrone (PBN) and Dimethyl-Pyrrolidine-N-oxide being the most representative examples for such uses.
On the other hand, it is well recognized that introduction of fluorine in organic molecules can be used for a fine tuning of their physical, chemical and biological properties. .
Then, the authors will extend it to molecules B with functional groups in terminal position of the alkyl chains.
Further, these groups could be also employed to graft easily various types of labels eventually required for in depth in vivo biological studies.
All these new nitrones will be prepared in short sequences (2-3 steps) from the easily available type-D gemdifluoroalkyl propargylic alcohols..
Results and Discussion
In order to prepare the first series of representative nitrones, the authors started from the known [21, 22] gem-difluoro propargylic derivative 1.
After reaction with n-BuLi at -90 °C, followed by addition of different aldehydes 2a-e, the gem-difluorinated alcohols 3a-e were obtained (Scheme 1, Table 1).
The reactions with nitromethane, or 2-nitropropane, in the presence of DBU afforded in fair to good yields the nitro intermediates 4a-e and 5a-e respectively.
In agreement with previous results, the first step of this domino process is likely the base-mediated isomerization of the propargylic alcohols into the corresponding (non-isolated) enones 3’a-e which are trapped in situ by the nitroalkane anions to give the desired molecules 4 or 5. .
Abstract: A state-of-the-art method was developed for repurposing nitrone-containing compounds in the chemosensory field, the ability of the designed molecules to chelate metal cations was evaluated, and their unprecedented solubility in water was confirmed. A facile, rapid, and solvent-free method of synthesizing small molecular mass chemosensors was developed by using a modulative α-aryl-N-aryl nitrone template. α-(Z)-Imidazol-4-ylmethylen-N-phenyl nitrone (Nit1) and α-(Z)-2-pyridyl-N-phenyl nitrone (Nit2) were prepared in 15 min, isolated in less than 60 min with ca. 90% yield, and screened against nine metal cations. Nit1 is a small-molecular-mass compound (188 g mol−1) that is water-soluble and has specificity for sensing Cu2+ with an association constant of K = 1.53 x 1010 and a limit of detection (LOD) of 0.06 ppm. These properties make Nit1 a competitive chemosensor for the detection of Cu2+ in aqueous solution. The nitrone-containing template used in this study is a step forward for new and small chemosensory entities.
TL;DR: This tutorial review provides a sampling of renowned fluorinated drugs and their mode of action with a discussion clarifying the role and impact of fluorine substitution on drug potency.
Abstract: It has become evident that fluorinated compounds have a remarkable record in medicinal chemistry and will play a continuing role in providing lead compounds for therapeutic applications. This tutorial review provides a sampling of renowned fluorinated drugs and their mode of action with a discussion clarifying the role and impact of fluorine substitution on drug potency.
TL;DR: The effects of the strategic incorporation of fluorine in drug molecules and applications in positron emission tomography are provided, as well as new synthetic methodologies that allow more facile access to a wide range of fluorinated compounds.
Abstract: The role of fluorine in drug design and development is expanding rapidly as we learn more about the unique properties associated with this unusual element and how to deploy it with greater sophistication. The judicious introduction of fluorine into a molecule can productively influence conformation, pKa, intrinsic potency, membrane permeability, metabolic pathways, and pharmacokinetic properties. In addition, 18F has been established as a useful positron emitting isotope for use with in vivo imaging technology that potentially has extensive application in drug discovery and development, often limited only by convenient synthetic accessibility to labeled compounds. The wide ranging applications of fluorine in drug design are providing a strong stimulus for the development of new synthetic methodologies that allow more facile access to a wide range of fluorinated compounds. In this review, we provide an update on the effects of the strategic incorporation of fluorine in drug molecules and applications in po...
TL;DR: Compounds Currently in Phase II−III Clinical Trials of Major Pharmaceutical Companies: New Structural Trends and Therapeutic Areas is presented.
Abstract: Compounds Currently in Phase II−III Clinical Trials of Major Pharmaceutical Companies: New Structural Trends and Therapeutic Areas Yu Zhou,† Jiang Wang,† Zhanni Gu,† Shuni Wang,† Wei Zhu,† Jose ́ Luis Aceña,*,‡,§ Vadim A. Soloshonok,*,‡,∥ Kunisuke Izawa,* and Hong Liu*,† †Key Laboratory of Receptor Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 555 Zu Chong Zhi Road, Shanghai 201203, China ‡Department of Organic Chemistry I, Faculty of Chemistry, University of the Basque Country UPV/EHU, Paseo Manuel Lardizab́al 3, 20018 San Sebastiań, Spain Department of Organic Chemistry, Autońoma University of Madrid, Cantoblanco, 28049 Madrid, Spain IKERBASQUE, Basque Foundation for Science, María Díaz de Haro 3, 48013 Bilbao, Spain Hamari Chemicals Ltd., 1-4-29 Kunijima, Higashi-Yodogawa-ku, Osaka, Japan 533-0024
TL;DR: Evidence is presented that a new class of free radical blocking agents, nitrone spin‐traps, may help not only to clarify if free radical events are involved, but may help prevent the development of injury in certain pathological conditions.
Abstract: Even though oxygen is necessary for aerobic life, it can also participate in potentially toxic reactions involving oxygen free radicals and transition metals such as Fe that damage membranes, proteins, and nucleic acids. Oxygen free radical reactions and oxidative damage are in most cases held in check by antioxidant defense mechanisms, but where an excessive amount of oxygen free radicals are produced or defense mechanisms are impaired, oxidative damage may occur and this appears to be important in contributing to several pathological conditions including aging, carcinogenesis, and stroke. Several newer methods, such as in vivo spin-trapping, have become available to monitor oxygen free radical flux and quantitate oxidative damage. Using a combination of these newer methods collectively focused on one model, recent results show that oxidative damage plays a key role in brain injury that occurs in stroke. Subtle changes, such as oxidative damage-induced loss of glutamine synthetase activity, may be a key ...
TL;DR: In this Perspective, applications of fluorine in the construction of bioisosteric elements designed to enhance the in vitro and in vivo properties of a molecule are summarized.
Abstract: The electronic properties and relatively small size of fluorine endow it with considerable versatility as a bioisostere and it has found application as a substitute for lone pairs of electrons, the hydrogen atom, and the methyl group while also acting as a functional mimetic of the carbonyl, carbinol, and nitrile moieties. In this context, fluorine substitution can influence the potency, conformation, metabolism, membrane permeability, and P-gp recognition of a molecule and temper inhibition of the hERG channel by basic amines. However, as a consequence of the unique properties of fluorine, it features prominently in the design of higher order structural metaphors that are more esoteric in their conception and which reflect a more sophisticated molecular construction that broadens biological mimesis. In this Perspective, applications of fluorine in the construction of bioisosteric elements designed to enhance the in vitro and in vivo properties of a molecule are summarized.