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Diaza [1,4] Wittig-type rearrangement of N-allylic-N-Boc-hydrazines into γ-amino-N-Boc-enamines was demonstrated. The scope and limitation, experimental mechanistic studies, and a proposed reaction mechanism were also described.

Pyrrolizidine or azabicyclo[3.3.0]-octane (Figure 1) and its derivatives are a very common azabicycle motif within natural products (pyrrolizidine alkaloids, PAs) possessing a bridge head nitrogen ...

A copper(II)/NafionNR50-catalyzed cascade is demonstrated, wherein in situ keteneimine formation and hydroarylation processes are involved. Various substituted 4-sulfonamidoquinolin-2-ones and various derivatives thereof were obtained. The robust toluenesulfonamide protecting group can be removed on demand in a mild light-promoted process to provide access to otherwise difficult to obtain 4-aminoquinolin-2-ones.

Ferrocenium salts can be easily obtained from ferrocene by either synthetic preparation or in situ reaction. The ferrocenium ion can act as a one-electron oxidant and thus initiate or promote a range of radical processes. Ferrocene itself can donate electrons to suitable substrates, resulting in useful transformations. Ferrocenium salts can also act as mild Lewis acids. This paper highlights various uses of ferrocenium ions in organic reactions. 1 Introduction 2 Ferrocenium Salts as Lewis Acids 3 Ferrocenium Salts as One-Electron Oxidants 4 Ferrocene as an Electron Donor 5 Catalysis with Other Ferrocenium Derivatives 6 Conclusions

Phase equilibria in the Hf–Ti–P system were investigated at T = 1070 K in the region 0–67 at.% of P, employing X-ray powder diffraction. The three ternary compounds exist in the Hf–Ti–P system at this temperature. Two of them have homogeneity regions and their compositions can be represented as Hf x Ti 2− x P (0.65 ⩽ x ⩽ 1.30; TiNiSi-type, space group Pnma , a = 6.130(3)–6.673(5), b = 3.508(2)–3.557(2), c = 8.050(5)–8.161(2) A) and Hf x Ti 2− x P 0.68 . (0.75 ⩽ x ⩽ 1.00; Zn 3 Cu-type, space group Р -6, a = 4.758(1)–4.803(1), c = 3.005(1)–3.035(1) A). The crystal structure of the new phosphide Hf 5.35 Ti 8.65 P 8.93 was determined by X-ray single crystal diffraction. This compound crystallizes with the Zr 14 P 9 -type structure (space group Pnnm , cell parameters a = 15.973(1), b = 26.335(2), c = 3.5281(2) A, R 1 = 0.0670; wR 2 = 0.0875). The majority of binary compounds form substitution type solid solutions, in their homogeneity ranges the substitution of Ti by Hf or Hf for Ti takes place.

N-Boc-1-amino-1,3-dienes are obtained with perfect stereoselectivity by base-promoted 1,4-elimination reactions of N-Boc-1-amino-4-methoxy-2-alkenes.

The extremely rapid and selective method tolerates multiple functional groups except the ones reacting with the reducing agent, hydrazine.

In gold nanoparticles the surface metal atoms play a major role, determining their chemical and physical properties by interacting with donor-acceptor species or ligands in a similar way as the related metal complexes. In addition, coherent oscillations of the metal electrons in resonance with the frequency of the exciting light give rise to localized surface plasmons responsible for an enhancement of the local electric field and SERS effect, allowing a wide range of applications in chemistry, biology and nanotechnology. Multifunctional bridging ligands can be employed for simultaneously binding metal ions and surface atoms. The attractive point of this approach is the possibility of exploiting the charge controlled stabilization by the metal complexes, while imparting new characteristics and properties to the modified nanoparticles. As a matter of fact, a new, exciting field of coordination chemistry can be envisaged, combining metal nanoparticles and metal complexes, in the light of supramolecular and surface plasmon resonance effects.

Roseic acid (Ia) and roseolactones A (IIb) and B (IIc) possessing an unusual furan moiety condensed to the B-ring are isolated from the title fungi.

In the reaction of 4-chlorocoumarin-3-carbaldehyde with malononitrile in the presence of piperidine, a piperidinium salt of a novel tricyclic chromeno[3,4-c]pyridine derivative was isolated instead of the expected “tert-amino effect” product. When hexamethyleneimine (azepane) was used as a base, the corresponding azepanium salt (same anion) was obtained. Both structures have been formulated on the basis of their spectral (IR, NMR, MS) behavior and elemental analyses. In addition, the structure of the piperidinium salt was confirmed by means of X-ray crystallographic analysis.

Chiral ferrocene derivatives belong to privileged ligand classes for asymmetric transition metal catalysed reactions. Hetero-bidentate phosphane ligands are hybrid ligands, which combine the properties of phosphorus with those of other donor atoms. This feature creates further asymmetry around the metal centre, which may be helpful for increasing the stereoinduction. Therefore, hetero-bidentate ligands are useful alternatives to homo-bidentate ligands. Ligands featuring phosphorus and nitrogen or sulphur are quite common. From among ferrocene catalysts, ferrocenyl amino phosphanes and phosphane oxazolines serve as excellent examples. Fesulphos and ThioClickFerrophos are notable P,S-ligand examples. On the other hand, combinations of phosphorus with oxygen or carbon are only beginning to show their potential in asymmetric catalysis. Another useful feature in ligands of this type is the markedly different coordination properties of donor atoms, resulting in interesting opportunities for catalysis. Ferrocenyl MOP-analogues or a fascinating combination of phosphane and secondary phosphane-oxide would represent this ligand class. The last section of the review focuses on phosphanes combined with carbon-based donor atoms that are phosphane-alkene and phosphane-carbene ligands. This review focuses on the applications of these hetero-bidentate ferrocene ligands in asymmetric catalysis with a special emphasis on the most recent and influential literature reports.

An efficient continuous flow process is elaborated for the methylation of indoles (I), phenols (IV), thiophenols (VI), and carboxylic acids (VIII) using in situ generated tributylmethylammonium methylcarbonate as a catalyst.

Carbon nanotubes (CNTs) are versatile nanomaterials with applications spanning from medicinal chemistry and biology, to electronics as field effect transistors or energy as fuel cells. The major drawback stems from the CNT insolubility in most of the organic and aqueous media, which severely hampers the material processability. To overcome this prob- lem, functionalization of CNTs is generally accomplished by either covalent strategies result- ing in the modification of the CNT backbone via radical reactions, fluorination, and/or cycloaddition reactions, or noncovalent protocols, exploiting multiple weak interactions (hydrophobic, van der Waals, electrostatic) with suitable reagents. Herein, we highlight that a rewarding approach includes a combination of covalent/noncovalent methods, by a tailored synthetic modification of the CNT surface with polycationic dendrimeric chains, fostering the successive decoration with a multimetallic and polyanionic water oxidation catalyst. The outcome is a hybrid nanomaterial with unperturbed CNT electrical properties, in close con- tact with a unique multi-electron catalyst enabling electrocatalytic water splitting with high efficiency at low overpotentials.

The popularity of dedicated microwave reactors in many academic and industrial laboratories has produced a plethora of synthetic protocols that are based on this enabling technology. In the majority of examples, transformations that require several hours when performed using conventional heating under reflux conditions reach completion in a few minutes or even seconds in sealed-vessel, autoclave-type, microwave reactors. However, one severe drawback of microwave chemistry is the difficulty in scaling this technology to a production-scale level. This Concept article demonstrates that this limitation can be overcome by translating batch microwave chemistry to scalable continuous-flow processes. For this purpose, conventionally heated micro- or mesofluidic flow devices fitted with a back-pressure regulator are employed, in which the high temperatures and pressures attainable in a sealed-vessel microwave chemistry batch experiment can be mimicked.

The method allows an improved access to various (pyrazolyl)carboxanilides which are inhibitors of transient receptor potential channels.

Microreactor technology and continuous flow processing in general are key features in making organic synthesis both more economical and environmentally friendly. Heterogeneous catalytic hydrogenation reactions under continuous flow conditions offer significant benefits compared to batch processes which are related to the unique gas-liquid-solid triphasic reaction conditions present in these transformations. In this review article recent developments in continuous flow heterogeneous catalytic hydrogenation reactions using molecular hydrogen are summarized. Available flow hydrogenation techniques, reactors, commonly used catalysts and examples of synthetic applications with an emphasis on laboratory-scale flow hydrogenation reactions are presented.

Cyclic secondary amines react with mono- or dichloronitrobenzene in the presence of a catalytic amount of cobalt(II) chloride. Phosphane ligands are beneficial for the reaction, although the bite-angle effect was not strong. The nitro-substituted tertiary amines formed are important as bioactive compounds and can also be intermediates for the synthesis of substituted anilines. This work represents the first cobalt-catalyzed approach to C-N bond-forming reactions involving aromatic chlorides and cyclic secondary amines. The reaction is ortho- and para-selective, with meta-substituted halides being unreactive in this procedure.

An unusual ring expansion was observed in the course of studies on the synthesis of berberine linked to oligonucleotides at the 13-position. Nitration of oxyberberine (1) gave 13-nitrooxyberberine (2) as the major product. Lithium aluminum hybride reduction of 2 gave ring-expansion product 4 in addition to the expected primary amine 5. The structure of 4, a novel B/C-cis fused ring system, was solved by X-ray crystallography

Methyl 6-O-butyryl-α-D- and -L-galactopyranoside and methyl 6-O-butyryl-α-D- and -L-mannopyranoside, which present three contiguous secondary hydroxy groups in different orientations, have been acylated using three hydrolytic enzymes. Porcine pancreatic, Candida cylindracea, and Pseudomonas fluorescens lipases in organic solvents. Some generalization of the obtained results is discussed. Methyl 6-O-butyryl-α-D- and -L-galactopyranoside and methyl 6-O-butyryl-α-D- and -L-mannopyranoside, which present three contiguous secondary hydroxy groups in different orientations, have been acylated using three hydrolytic enzymes. Porcine pancreatic, Candida cylindracea, and Pseudomonas fluorescens lipases in organic solvents. Some generalization of the obtained results is discussed.

2-Methylpentan-3-ol stereospecifically labelled with deuterium on one of the isopropyl methyl groups has been synthesized, thus allowing the unequivocal assignment of their 13C NMR resonances. 13C NMR assignments for these groups proposed earlier are shown to be incorrect. Involvement in the biosynthesis of the 24β-ethylsterol poriferasterol in the crysophyte Ochromonas malhamensis is discussed.

3-Trans-cinnanyl-8-propionyl-3,8-diazabicyclo[3,2,1]octane 1 , its monocyclic analog 4-trans-cinnamyl-1-propionyl-cis-2,6-dimethylpiperazine 2 and their isomers having the nitrogen sustituents exchanged, 3 and 4 , have been submitted to conformational analysis by molecular mechanics and 1 H NMR spectroscopy. The results of molecular modeling indicate that, while the monocyclic compound 2 has a preferred conformation very similar to the corresponding bicyclic compound 1 , compound 4 is quite different with respect to 3 ; it is the only compound with equatorially oriented substituents on the carbon atoms of the hexacyclic ring. This feature could explain the low affinity of 4 towards μ receptors, as compared with the high affinity of 1 – 3 .

Rearrangement of the tricarbonyl(cycloheptatriene)iron derivative 1 to 2 and 3 took place very readily in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) at room temperature. This finding is in striking contrast to the stability of 1 in MeOH under otherwise similar conditions. The isomerization processes which give rise to an equilibrium among 1, 2 and 3 must involve zwitterionic intermediates of the type 4, whose formation, consequently, is highly favored by HFIP. Heating 9 in HFIP brought about its rearrangement to 15. We suggest that formation of the zwitterionic intermediate 12 triggers a rearrangement of the carbocyclic moiety which can take place as a result of the high polarity and low nucleophilicity of HFIP. The rearrangement 9 → 15 could not be achieved by using other polar solvents such as methanol or nitromethane. This observation once again demonstrates how suitable HFIP is as a medium for isomerizations via zwitterionic intermediates. The role of traces of free acid, present even in purified HFIP, is discussed.

A regio- and stereoselective didehydrodimerization procedure, whose key step involves the anodic oxidation, allows the conversion of β-anilinoacrylic alkaloids belonging to the Aspidosperma class, typified by tabersonine (1) and its 3-oxo derivative 2, into the hitherto unknown 16,10′-didehydro dimers 3 and 7, respectively.

The synthesis of ferrocenyl-substituted thiophenes, furans, pyrroles, pyrimidine and pyrazole has been studied. 2-Ferrocenylpyrroles were prepared from ferrocenyl ketoximes and acetylene in DMSO - KOH mixture whereas 3-chloro-3-ferrocenylacrylaldehydes and thioglycolic or glycolic acids were the starting materials for the synthesis of the thiophene and furan derivatives. The yields were significantly enhanced when the reactions were carried out in a microwave oven. The lower stability of 2-ferrocenylfuran in comparison with 2-ferrocenylthiophene is discussed on the basis of semiempirical quantum chemistry calculations.

Friedel-Crafts acetylation, Vilsmeier-Haack formylation and BuLi metallation followed by DMF quenching of 2-ferrocenylthiophene, 2-ferrocenyl-3-phenylthiophene, 2-ferrocenyl-5-phenylthiophene, 2-ferrocenyl-1-methylpyrrole and 2-ferrocenyl-1-methyl-3-phenylpyrrole have been studied. The ferrocene behaved as a strong electron donor and electrophilic substitution took place at the heteroarene ring, the only exception being the Friedel-Crafts acetylation of 2-ferrocenyl-1-methylpyrrole. The course of formylation of 2-ferrocenyl-5-phenylthiophene was dependent on the applied method. Vilsmeier-Haack formylation gave 3-formyl-, and BuLi/DMF gave 4-formyl derivative. The product of 2-ferrocenylthiophene dimerization was isolated as the side product of its Friedel-Crafts acetylation.

The synthesis and pharmacological evaluation of a series of pyrrolidine analogues of thymoxamine allowed access to the basic SAR for the aromatic substitution pattern. The results confirm the relevance of the simultaneous presence of the hydroxy and methyl groups on the benzene ring and prompted us to prepare the corresponding indole congener. The principle of the phenol—indol bioisosterism was confirmed by the results obtained. The introduction of the N -(2-methoxyphenyl)piperazine moiety instead of pyrrolidine changed the receptor affinity profile and introduced a good uroselectivity.

Reasonable yields (60–70 %) of aromatic α-disulfones can be obtained in short reaction times from a sonicated mixture of an arenesulfonyl chloride and lithium in THF.

Several monocyclic derivatives structurally related to the μ-opioid agonist 3-cinnamyl-8 propionyl-3,8-diazabicyclo[3.2. 1]octane have been synthesized and tested in binding studies using the μ-selective 3 H-DAMGO as ligand. Modeling studies have been performed on the same compounds in order to explain the observed lack of affinity towards μ-opioid receptors

The Diels−Alder reactions of 1,3-diphenylisobenzofuran with acryloylferrocene (1), 4-ferrocenyl-3-buten-2-one (2), cinnamoylferrocene (3), 3-ferrocenyl-1-phenyl-2-propenone (4), chalcone (5), 1-((η6-phenyl)tricarbonylchromio)-3-phenyl-2-propenone (6), 1-phenyl-3-((η6-phenyl)tricarbonylchromio)-2-propenone (7), and (2-nitrovinyl)ferrocene (8) were examined under various conditions. The best results were achieved using SiO2 and a very acidic montmorillonite clay, KSF, as the catalyst, and the reactions were carried out without solvent. Reasonable to good yields of the Diels−Alder (D-A) products were isolated in most cases. X-ray structural studies showed that the adducts 13b and 13h, derived from the (E)-alkenes 2 and 8, have exo-acetyl or -nitro substituents and endo-ferrocenyl groups with respect to the bridging oxygen atom of the 7-oxabicycloheptane ring system. The product 13a from the monosubstituted enone 1 also has an exo-acyl (ferrocenylcarbonyl) group. Aluminum chloride was found to be a good catal...