Strain-Release-Driven Modular Synthesis of Oxetane-Based Amide Bioisosteres: Concise, Robust and Scalable Approach.

Amide bioisoterism is a widely used strategy in drug development to fine-tune physicochemical, pharmacokinetic, and metabolic properties, eliminate toxicity and gain intellectual property rights in uncharted chemical space. Of these, oxetane-amines offer particularly exciting possibilities as bioisosteres, although they are less frequently investigated than warranted due to the lack of simple and widely applicable synthetic methods. Herein, we report a two-step, practical, modular, robust, and scalable method for the construction of oxetane-containing amide bioisosteres that relies on the readily available oxetan-3-one. This operationally simple procedure exploits the enhanced reactivity of the keto group of the commercially available oxetan-3-one to form amine-benzotriazole intermediates, which springloaded adducts are then reacted with various aliphatic and aromatic organometallic reagents under mild conditions to afford various amino-oxetanes in good to high yields. The simplicity and broad applicability of the method greatly facilitates the synthesis of derivatives that were previously difficult or impossible to produce. The usefulness of this method in the field medicinal chemistry was also demonstrated by eliminating the well-known metabolic problem of ketoconazole.

Total Synthesis and Structural Plasticity of Kratom Pseudoindoxyl Metabolites.

Mitragynine pseudoindoxyl, a kratom metabolite, has attracted increasing attention due to its favorable side effect profile as compared to conventional opioids. Herein, we describe the first enantioselective and scalable total synthesis of this natural product and its epimeric congener, speciogynine pseudoindoxyl. The characteristic spiro-5-5-6-tricyclic system of these alkaloids was formed through a protecting-group-free cascade relay process in which oxidized tryptamine and secologanin analogues were used. Furthermore, we discovered that mitragynine pseudoindoxyl acts not as a single molecular entity but as a dynamic ensemble of stereoisomers in protic environments; thus, it exhibits structural plasticity in biological systems. Accordingly, these synthetic, structural, and biological studies provide a basis for the planned design of mitragynine pseudoindoxyl analogues, which can guide the development of next-generation analgesics.

Revealing Long-Range Substituent Effects in the Laser-Induced Fluorescence and Dispersed Fluorescence Spectra of Jet-Cooled CHxF3-xCH2O (x = 1, 2, 3) Radicals.

The B̃-X̃ laser-induced fluorescence (LIF) and dispersed fluorescence (DF) spectra of the atmospherically important ß-monofluoro ethoxy (MFEO), ß,ß-difluoro ethoxy (DFEO), and ß,ß,ß-trifluoro ethoxy (TFEO) radicals were recorded with vibronic resolution under jet-cooled conditions. To simulate the spectra, Franck-Condon factors were obtained from quantum chemical computations carried out at the CAM-B3LYP/6-311++G(d,p) level of theory. The simulations reproduce well both the LIF and DF spectra. Both conformers (G and T) of MFEO and one (G) of the two conformers of DFEO contribute to the LIF spectrum. A comparison between the experimental and calculated spectra confirms the expected long-range field effects of the CHxF3-x group on electronic transition energies and bond strengths, especially in the excited electronic (B̃) state. Although TFEO has only one conformer, its LIF spectrum is highly congested, which is attributed to the interaction between CO stretch and the -CF3 internal rotation.

Development of fast-dissolving dosage forms of curcuminoids by electrospinning for potential tumor therapy application.

Curcuminoids (CUs) of antitumor and various other potential biological activities have extremely low water solubility therefore special formulation was elaborated. New fast dissolving reconstitution dosage forms of four CUs were prepared as fibrous form of 2-hydroxypropyl-ß-cyclodextin (HP-ß-CD). In the electrospinning process HP-ß-CD could act both as solubilizer and fiber-forming agent. The solubilization efficiency of the CU-HP-ß-CD systems was determined with phase-solubility measurements. The electrospun CUs were amorphous and uniformly distributed in the fibers according to XRD analysis and Raman mappings. The fibrous final products had fast (<5 min) and complete dissolution. In typical iv. infusion reconstitution volume (20 mL) fibers containing 40-80 mg of CU could be dissolved, which is similar to the currently proposed dose (<120 mg/m2). The in vitro cytostatic effect data showed that the antitumor activity of the CU-HP-ß-CD complexes was similar or better compared to the free APIs.

Facile isolation and analysis of sporopollenin exine from bee pollen.

We present facile methods to obtain purified sporopollenin exine capsules, and provide mass balances for classical and novel purification procedures. An ionic liquid, tetrabutyl phosphonium hydroxide turned out to be the most effective in removing the intine wall. The sporopollenin capsules were investigated by fluorescent microscopy, AFM, solid-state NMR and infrared Raman spectroscopy. The latter two methods showed that sunflower and rape exines have different proportions of O-aliphatic and aromatic constituents. Purified exine capsules were coated with functionalized fluorophores. The procedures presented in this paper could contribute to further spread of the applications of this hollow, and chemically highly resistant material.

Liver-on-a-Chip‒Magnetic Nanoparticle Bound Synthetic Metalloporphyrin-Catalyzed Biomimetic Oxidation of a Drug in a Magnechip Reactor.

Biomimetic oxidation of drugs catalyzed by metalloporphyrins can be a novel and promising way for the effective and sustainable synthesis of drug metabolites. The immobilization of 5,10,15,20-tetrakis(2,3,4,5,6-pentafluorophenyl)iron(II) porphyrin (FeTPFP) and 5,10,15,20-tetrakis-(4-sulfonatophenyl)iron(II) porphyrin (FeTSPP) via stable covalent or rapid ionic binding on aminopropyl-functionalized magnetic nanoparticles (MNPs-NH2) were developed. These immobilized catalysts could be efficiently applied for the synthesis of new pharmaceutically active derivatives and liver related phase I oxidative major metabolite of an antiarrhythmic drug, amiodarone integrated in a continuous-flow magnetic chip reactor (Magnechip).