Synthesis of exo-Imidazolidin-2-one Dienes, Their Isomerization, and Selectivity in Diels-Alder Cycloadditions

An efficient and alternative synthesis of exo-imidazolidin-2-one dienes is described. A condensation reaction was carried out with bis-imino derivatives, diacetyl, and triphosgene, affording symmetrically N, N-disubstituted dienes. The use of alkyl methyl α-diketones led to the formation of nonsymmetrical dienes, which underwent isomerization to provide more stable inner-outer-ring dienes under Lewis acid conditions. Evaluation was made of the reactivity as well as regio- and stereoselectivity of these dienes in Diels-Alder reactions. They proved to be highly reactive and selective. DFT calculations of the transition states accounted for their behavior.

Synthesis of Novel Hybrid 4H-Pyran-lipoic and 4H-Pyran-azetidine Derivatives

In this study, a molecular hybridization strategy was used to design and synthesize two novel series of hybrid compounds: 4H-pyran-lipoic and 4H-pyran-azetidine, employing ammonium hydroxide and involving the participation of aldehydes, malononitrile, and compounds derived from β-ketoesters to obtain the products with good yields.

Divergent and Selective Functionalization of 2-Formylpyrrole and its Application in the Total Synthesis of the Aglycone Alkaloid Pyrrolemarumine

Diverse 1,2- and 1,2,5-substituted pyrroles were efficiently prepared through a regioselective functionalization of 2-formylpyr-role (<strong>5a</strong>). This methodology was applied for the first total synthesis of pyrrolemarumine (<strong>4b</strong>), the aglycone of the corresponding natural pyr-role alkaloid 4”-O-a-L-rhamnopyranoside. The synthesis of <strong>4b</strong> was achieved starting from 5a through a seven-step process in 28% over-all yield.

Infrared Irradiation-Assisted Multicomponent Synthesis of 2-Amino-3-cyano-4H-pyran Derivatives

A simple, versatile, and efficient synthesis of 4<em>H</em>-pyran derivative compounds is achieved via a three-component cyclocondensation of aldehydes, malononitrile, and ethyl acetoacetate, using ammonium hydroxide as the catalyst, promoted by infrared irradiation. The present method offers several advantages, such as high yields, non hazardous reaction conditions as well as short reaction times.

A Green Approach to the Production of 2-pyridone Derivatives Promoted by Infrared Irradiation

<p>An alternative is presented for promoting a reaction with infrared irradiation to obtain different 4-aryl-3-cyano-5-ethoxycarbonyl-6-methyl-2-pyridone derivatives <strong>9a-k</strong>. The process was carried out with a green approach from the corresponding 4<em>H</em>-pyrans, using mild reaction conditions and infrared irradiation as the energy source. In the first stage, the reaction produced 1,2,3,4-tetrahydropyridin-2-one derivatives <strong>8a-k</strong>, followed by an oxidative step to afford the target molecules in good yields. The structure of products <strong>9a-k</strong> was confirmed by FT-IR, ¹H NMR and ¹³C NMR spectroscopic techniques and X-ray diffraction. It was found that the efficiency of the reaction depends on the catalyst and the solvent, as well as on the aldehyde substituents.</p>

Palladium-Catalyzed Synthesis of Diarylamines and 1- and 2-Oxygenated Carbazoles: Total Syntheses of Natural Alkaloids Clauraila A, Clausenal, Clausine P, and 7-Methoxy-O-methylmukonal

The scope and limitations of the strategy for the conversion of 2-anilinocyclohexenones and N-arylcyclohexane enaminones into the 1- and 2-oxygenated carbazole scaffolds, respectively, were evaluated. The one-pot palladium(0)-catalyzed aromatization/methylation process of the aforementioned substrates provided a diversity of the corresponding diarylamines. A subsequent palladium(II)-catalyzed cyclization of the latter delivered the desired 1- and 2-oxygenated carbazoles in good overall yields. Special attention was given to the synthesis of the uncommon 1,8-disubstituted carbazoles. This methodology was employed for the total synthesis of the naturally occurring clauraila A, clausenal, clausine P, and 7-methoxy-O-methylmukonal.

Complex magnetic orders in small cobalt–benzene molecules

Organometallic clusters based on transition metal atoms are interesting because of their possible applications in spintronics and quantum information processing.

Cattle are a potential reservoir of bubaline herpesvirus 1 (BuHV1)

In the present work, controlled experimental infection and transmission studies in domestic cattle (Bos taurus) and water buffaloes (Bubalus bubalis) were carried out to study the in vivo behaviour of bubaline herpesvirus 1 (BuHV1). Two bovine and two buffalo calves were infected with BuHV1 (20287N isolate) by intranasal aerosolisation. Two sentinel cattle did not receive the virus challenge, but were housed with infected buffaloes to evaluate horizontal transmission. All experimentally inoculated animals showed viral infection and respiratory clinical signs. BuHV1 experimentally infected calves showed intermittent viral excretion between 2 days and 18 days postinfection (dpi) with a maximum titre of excretion of 10⁶ TCID₅₀/ml and moderate rhinitis between 2 dpi and 20 dpi. BuHV1 experimentally inoculated buffaloes showed mild respiratory signs, which consisted mainly of serous nasal secretions during the infection period. Sentinel calves showed mucosal specific IgG₁ antibodies at seven days postcontact. Viral DNA was detected by PCR and sequencing in both buffaloes and sentinel calves, which could be associated with latency. In conclusion, this study showed the susceptibility of cattle to BuHV1 after both experimental infection and contact with infected buffaloes. These data increase the scarce knowledge on the pathogenesis in natural host and the susceptibility of cattle to BuHV1 experimental infection.

Condensation of Diacetyl with Alkyl Amines: Synthesis and Reactivity of p-Iminobenzoquinones and p-Diiminobenzoquinones

Condensation reactions between diacetyl and α-branched primary alkylamines under mild and neutral conditions provided a mixture of 2,5-dimethylbenzoquinone(alkylimines), 2,5-dimethylbenzoquinone(bis-alkyldiimines), and N,N'-dialkyl-2,5-dimethylbenzene-1,4-diamines, which were efficiently separated as pure products by column chromatography. Both 2,5-dimethylbenzoquinone(alkylimines) and 2,5-dimethylbenzoquinone(bis-alkyldiimines) underwent an interchange of the alkylimino group when treated with anilines, followed by reductive aromatization, to provide diarylamines and 1,4-dianilinobenzenes, respectively. Evaluation was also made of the reactivity and selectivity of these compounds in the presence of anilines, thiophenols and alkylhalides.

The Butterflies of Barro Colorado Island, Panama: Local Extinction since the 1930s

Few data are available about the regional or local extinction of tropical butterfly species. When confirmed, local extinction was often due to the loss of host-plant species. We used published lists and recent monitoring programs to evaluate changes in butterfly composition on Barro Colorado Island (BCI, Panama) between an old (1923-1943) and a recent (1993-2013) period. Although 601 butterfly species have been recorded from BCI during the 1923-2013 period, we estimate that 390 species are currently breeding on the island, including 34 cryptic species, currently only known by their DNA Barcode Index Number. Twenty-three butterfly species that were considered abundant during the old period could not be collected during the recent period, despite a much higher sampling effort in recent times. We consider these species locally extinct from BCI and they conservatively represent 6% of the estimated local pool of resident species. Extinct species represent distant phylogenetic branches and several families. The butterfly traits most likely to influence the probability of extinction were host growth form, wing size and host specificity, independently of the phylogenetic relationships among butterfly species. On BCI, most likely candidates for extinction were small hesperiids feeding on herbs (35% of extinct species). However, contrary to our working hypothesis, extinction of these species on BCI cannot be attributed to loss of host plants. In most cases these host plants remain extant, but they probably subsist at lower or more fragmented densities. Coupled with low dispersal power, this reduced availability of host plants has probably caused the local extinction of some butterfly species. Many more bird than butterfly species have been lost from BCI recently, confirming that small preserves may be far more effective at conserving invertebrates than vertebrates and, therefore, should not necessarily be neglected from a conservation viewpoint.

Endovascular treatment of intracranial aneurysms using the Pipeline Flex embolization device: a case series of 30 consecutive patients

BACKGROUND

The Pipeline Flex embolization device has some peculiarities in comparison with the previous generation device. Despite recent reports of the modified delivery system, its safety is still unknown.

OBJECTIVE

To illustrate the intraprocedural and periprocedural complication rate with this new device in 30 consecutive patients.

MATERIAL AND METHODS

Clinical, procedural, and angiographic data, including aneurysm size and location, device or devices used, angiographic and clinical data were analyzed.

RESULTS

30 patients harboring 30 aneurysms were analyzed. 39 devices were placed properly. Multiple Pipeline embolization devices (PEDs) were used in 7 cases. In 28 devices the distal end opened fully from the beginning with a complete wall apposition. In the remaining 11 devices, distal-end opening of the devices was instant but partial, but fully opened easily after recapture. Among the 30 procedures, recapture and reposition of the Pipeline Flex was performed four times owing to proximal migration/malposition of the device during delivery. Four intraprocedural/periprocedural complications occurred, of which 2 resulted in major complications, with neurologic deficits persisting for longer than 7 days. The 30-day morbidity rate was 6.6%, with no deaths. No aneurysm rupture or parenchymal hemorrhage was seen.

CONCLUSIONS

The Pipeline Flex embolization device allows more precise and controlled deployment than the first-generation device. The number of devices and the complication rate during the learning curve are lower than reported with the first-generation PED. The new delivery system and the resheathing maneuvers do not seem to increase the intraprocedural complication rate in comparison with the first-generation PED.

Synthesis of novel polysubstituted N-benzyl-1H-pyrroles via a cascade reaction of alkynyl Fischer carbenes with α-imino glycine methyl esters

An efficient synthesis of N-benzyl-1H-pyrroles is described by a 1,4-addition/isomerization/ring closure/demetalation process of alkynyl Fischer carbene and iminoester.

Imaging of spin waves in atomically designed nanomagnets

The spin dynamics of all ferromagnetic materials are governed by two types of collective phenomenon: spin waves and domain walls. The fundamental processes underlying these collective modes, such as exchange interactions and magnetic anisotropy, all originate at the atomic scale. However, conventional probing techniques based on neutron and photon scattering provide high resolution in reciprocal space, and thereby poor spatial resolution. Here we present direct imaging of standing spin waves in individual chains of ferromagnetically coupled S = 2 Fe atoms, assembled one by one on a Cu(2)N surface using a scanning tunnelling microscope. We are able to map the spin dynamics of these designer nanomagnets with atomic resolution in two complementary ways. First, atom-to-atom variations of the amplitude of the quantized spin-wave excitations are probed using inelastic electron tunnelling spectroscopy. Second, we observe slow stochastic switching between two opposite magnetization states, whose rate varies strongly depending on the location of the tip along the chain. Our observations, combined with model calculations, reveal that switches of the chain are initiated by a spin-wave excited state that has its antinodes at the edges of the chain, followed by a domain wall shifting through the chain from one end to the other. This approach opens the way towards atomic-scale imaging of other types of spin excitation, such as spinon pairs and fractional end-states, in engineered spin chains.

[Neuroimaging follow-up of cerebral aneurysms treated with endovascular techniques]

There are no specific recommendations in clinical guidelines about the best time, imaging tests, or intervals for following up patients with intracranial aneurysms treated with endovascular techniques. We reviewed the literature, using the following keywords to search in the main medical databases: cerebral aneurysm, coils, endovascular procedure, and follow-up. Within the Cerebrovascular Disease Group of the Spanish Society of Neuroradiology, we aimed to propose recommendations and an orientative protocol based on the scientific evidence for using neuroimaging to monitor intracranial aneurysms that have been treated with endovascular techniques. We aimed to specify the most appropriate neuroimaging techniques, the interval, the time of follow-up, and the best approach to defining the imaging findings, with the ultimate goal of improving clinical outcomes while optimizing and rationalizing the use of available resources.

Local probe of fractional edge states of S=1 Heisenberg spin chains

Spin chains are among the simplest physical systems in which electron-electron interactions induce novel states of matter. Here we propose to combine atomic scale engineering and spectroscopic capabilities of state of the art scanning tunnel microscopy to probe the fractionalized edge states of individual atomic scale S=1 spin chains. These edge states arise from the topological order of the ground state in the Haldane phase. We also show that the Haldane gap and the spin-spin correlation length can be measured with the same technique.

Synthesis, ex vivo and in silico studies of 3-cyano-2-pyridone derivatives with vasorelaxant activity

An efficient and simple synthesis of 3-cyano-2-pyridone derivatives (6a-f) through 3,4-dihydropyridin-2-one oxidation process is described. A greener method to synthesize 3,4-dihydropyridin-2-one has also been developed by rearranging 4H-pyran (4a-f) derivatives in aqueous medium applying H₂SO₄ as the catalyst source and microwave irradiation. The vasorelaxant activity of 3-cyano-2-pyridone derivatives (6a-f) was proved on isolated thoracic aorta rat rings with and without endothelium (+E and -E, respectively) pre-contracted with noradrenaline (0.1 μM). All compounds exhibited significant concentration-dependent and endothelium-independent vasorelaxant effects being the nitro derivatives (6a and f) and compound 6d the most potent with EC₅₀ of 7, 4.4 and 5 μM, respectively. Finally, a previously described 3D model of the central pore of human L-type calcium channel (LCC), modified to be on agreement with NCBI sequence NP_005174.2 for subunit alpha-1F isoform 1, was used to dock most active compounds. 6a, d and f lowest affinity energy structures were found docked in the same cavity conformed by IS6, IS5, IP and IIS6 helices. Nifedipine lowest energy structure was found in the cavity formed by IIS6, IIS5, IIP and IIIS6. Although nifedipine docked in a different cavity, the superposition of both, allowed us to observe that they were almost the same cavities, indicating that there exist subtle steric differences that lead to a different docking for nifedipine. All compounds docked with similar free energy of binding.