Cu-Catalyzed iminative hydroolefination of unactivated alkynes en route to 4-imino-tetrahydropyridines and 4-aminopyridines.

A general method for synthesizing 4-imino tetrahydropyridine derivatives is achieved, from readily available ß-enaminones and sulfonyl azides, which comprises a sequential copper catalyzed ketenimine formation and its hitherto inaccessible intramolecular hydrovinylation. The products are shown as ready precursors for highly valuable 4-sulfonamidopyridine derivatives via DDQ mediated oxidation.

An Ultrahydrophobic Fluorous Metal-Organic Framework Derived Recyclable Composite as a Promising Platform to Tackle Marine Oil Spills.

Derived from a strategically chosen hexafluorinated dicarboxylate linker aimed at the designed synthesis of a superhydrophobic metal-organic framework (MOF), the fluorine-rich nanospace of a water-stable MOF (UHMOF-100) exhibits excellent water-repellent features. It registered the highest water contact angle (≈176°) in the MOF domain, marking the first example of an ultrahydrophobic MOF. Various experimental and theoretical studies reinforce its distinctive water-repellent characteristics, and the conjugation of superoleophilicity and unparalleled hydrophobicity of a MOF material has been coherently exploited to achieve real-time oil/water separation in recyclable membrane form, with significant absorption capacity performance. This is also the first report of an oil/water separating fluorinated ultrahydrophobic MOF-based membrane material, with potential promise for tackling marine oil spillages.

Crystal structures of the pyrazinamide-p-aminobenzoic acid (1/1) cocrystal and the transamidation reaction product 4-(pyrazine-2-carboxamido)benzoic acid in the molten state.

The synthesis of pharmaceutical cocrystals is a strategy to enhance the performance of active pharmaceutical ingredients (APIs) without affecting their therapeutic efficiency. The 1:1 pharmaceutical cocrystal of the antituberculosis drug pyrazinamide (PZA) and the cocrystal former p-aminobenzoic acid (p-ABA), C7H7NO2·C5H5N3O, (1), was synthesized successfully and characterized by relevant solid-state characterization methods. The cocrystal crystallizes in the monoclinic space group P21/n containing one molecule of each component. Both molecules associate via intermolecular O-H···O and N-H···O hydrogen bonds [O···O = 2.6102 (15) Šand O-H···O = 168.3 (19)°; N···O = 2.9259 (18) Šand N-H···O = 167.7 (16)°] to generate a dimeric acid-amide synthon. Neighbouring dimers are linked centrosymmetrically through N-H···O interactions [N···O = 3.1201 (18) Šand N-H···O = 136.9 (14)°] to form a tetrameric assembly supplemented by C-H···N interactions [C···N = 3.5277 (19) Šand C-H···N = 147°]. Linking of these tetrameric assemblies through N-H···O [N···O = 3.3026 (19) Šand N-H···O = 143.1 (17)°], N-H···N [N···N = 3.221 (2) Šand N-H···N = 177.9 (17)°] and C-H···O [C···O = 3.5354 (18) Šand C-H···O = 152°] interactions creates the two-dimensional packing. Recrystallization of the cocrystals from the molten state revealed the formation of 4-(pyrazine-2-carboxamido)benzoic acid, C12H9N3O3, (2), through a transamidation reaction between PZA and p-ABA. Carboxamide (2) crystallizes in the triclinic space group P1̅ with one molecule in the asymmetric unit. Molecules of (2) form a centrosymmetric dimeric homosynthon through an acid-acid O-H···O hydrogen bond [O···O = 2.666 (3) Šand O-H···O = 178 (4)°]. Neighbouring assemblies are connected centrosymmetrically via a C-H···N interaction [C···N = 3.365 (3) Šand C-H···N = 142°] engaging the pyrazine groups to generate a linear chain. Adjacent chains are connected loosely via C-H···O interactions [C···O = 3.212 (3) Šand C-H···O = 149°] to generate a two-dimensional sheet structure. Closely associated two-dimensional sheets in both compounds are stacked via aromatic π-stacking interactions engaging the pyrazine and benzene rings to create a three-dimensional multi-stack structure.

Drug-Drug Molecular Salt Hydrate of an Anticancer Drug Gefitinib and a Loop Diuretic Drug Furosemide: An Alternative for Multidrug Treatment.

A 1:1 monohydrate salt containing gefitinib, an orally administrated chemotherapy treatment for lung and breast cancers and furosemide, a loop diuretic drug, commonly used in the treatment of hypertension and edema, has been prepared. The molecular salt crystallized in triclinic P-1 space group. The C-O bond lengths (~1.26 Å) in the COOH group show that proton transfer has occurred from furosemide to morpholine moiety of the gefitinib suggesting cocrystal to be ionic. The morpholine moiety of the gefitinib showed significant conformational change because of its involvement in conformation dictating the strong N-H···O hydrogen bonding interaction. The strong hydrogen bonding interaction between gefitinib and furosemide places their benzene rings in stacking mode to facilitate the generation of π-stack dimers. The neighboring dimers are bridged to each other via water molecule through N-H···O, C-H···O, O-H···N, and O-H···O interactions. The remarkable stability of the salt hydrate could be attributed to the strong hydrogen bonding interactions in the crystal structure. Interestingly, release of water from the lattice at 140°C produced new anhydrous salt that has better solubility and dissolution rate than salt hydrate. The drug-drug molecular salt may have some bearing on the treatment of patient suffering from anticancer and hypertension.

Highly emissive organic solids with remarkably broad color tunability based on N,C-chelate, four-coordinate organoborons.

Molecular fluorophores based on N,C-chelate, four-coordinate organoborons exhibit tunable solid-state emission colors that cover the whole visible region from blue to red. The emission color can be tuned through the substituents on either quinolines or the boron center.

Reaction of N-heterocyclic carbenes with chalcones leading to the synthesis of deoxy-Breslow intermediates in their oxidized form.

The synthesis of deoxy-Breslow intermediates in their oxidized form has been developed via the reaction of N-heterocyclic carbenes (NHCs) with chalcones. Moreover, the initial tetrahedral adduct formed from the 1,4-addition of NHCs to chalcones is also isolated.

Reversal of H-bonding direction by N-sulfonation in a synthetic reverse-turn peptide motif.

This communication depicts an intriguing example of hydrogen-bonding reversal upon introduction of a sulfonamide linkage at the N-terminus of a synthetic reverse-turn peptide motif. The ready availability of two sulfonyl oxygen atoms, as hydrogen-bonding acceptors, combined with the inherent twisted conformation of sulfonamides are seen to act as switches that engage/disengage the hydrogen-bond at the sticky ends/termini.

Catalyst-dependent selectivity in the relay catalytic branching cascade.

The synthesis of small organic molecules as probes for discovering new therapeutic agents has been an important aspect of chemical biology. One of the best ways to access collections of small molecules is to use various techniques in diversity-oriented synthesis (DOS). Recently, a new form of DOS, namely "relay catalytic branching cascades" (RCBCs), has been introduced, wherein a common type of starting material reacts with several scaffold-building agents (SBAs) to obtain structurally diverse molecular scaffolds under the influence of catalysts. Herein, the RCBC reaction of a common type of substrate with SBAs is reported to give two different types of molecular scaffolds and their formation is essentially dependent on the type of catalyst used.