Rhodium‐Catalyzed Annulation of ortho‐Alkenyl Anilides with Alkynes: Formation of Unexpected Naphthalene Adducts

This is the peer reviewed version of the following article: Seoane, A., Comanescu,C., Casanova, N., García-Fandiño, R., Diz, X., Mascareñas, J.L., Gulías, M. (2019), Rhodium-catalyzed annulation of ortho-alkenylanilides with alkynes: Formation of unexpected naphthalene adducts. AngewChemIntEd., 58,1700-1717 [doi: 10.1002/anie.201811747]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for self-archivingThis research received financial support through Spanish grants SAF2016‐76689‐R and CTQ2016‐77047‐P, from the Consellería de Cultura, Educación e Ordenación Universitaria (ED431C 2017119‐041, 2015‐CP082 and Centro Singular de Investigación de Galicia accreditation 2016‐2019, ED431G/09), the European Regional Development Fund (ERDF), and the European Research Council (Advanced Grant No. 340055). R.G.‐F. thanks the Spanish Government MINECO for a Ramon y Cajal (RYC‐RYC‐2016‐20335) contract. The orfeo‐cinqa network CTQ2016‐81797‐REDC is kindly acknowledged. All calculations were carried out at Centro de Supercomputación de Galicia (CESGA)S

Funeral at Dawn

2-Alkenyltriflylanilides react with allenes upon treatment with catalytic amounts of Pd­(OAc)₂ and Cu­(II) to give highly valuable 2,3-dihydro-1<i>H</i>-benzo­[<i>b</i>]­azepines, in good yields, and with very high regio- and diastereoselectivities. Density functional theory (DFT) calculations suggest that the C–H activation of the alkenylanilide involves a classical concerted metalation–deprotonation (CMD) mechanism

Complex Metal Borohydrides: From Laboratory Oddities to Prime Candidates in Energy Storage Applications

Despite being the lightest element in the periodic table, hydrogen poses many risks regarding its production, storage, and transport, but it is also the one element promising pollution-free energy for the planet, energy reliability, and sustainability. Development of such novel materials conveying a hydrogen source face stringent scrutiny from both a scientific and a safety point of view: they are required to have a high hydrogen wt.% storage capacity, must store hydrogen in a safe manner (i.e., by chemically binding it), and should exhibit controlled, and preferably rapid, absorption–desorption kinetics. Even the most advanced composites today face the difficult task of overcoming the harsh re-hydrogenation conditions (elevated temperature, high hydrogen pressure). Traditionally, the most utilized materials have been RMH (reactive metal hydrides) and complex metal borohydrides M(BH4)x (M: main group or transition metal; x: valence of M), often along with metal amides or various additives serving as catalysts (Pd2+, Ti4+ etc.). Through destabilization (kinetic or thermodynamic), M(BH4)x can effectively lower their dehydrogenation enthalpy, providing for a faster reaction occurring at a lower temperature onset. The present review summarizes the recent scientific results on various metal borohydrides, aiming to present the current state-of-the-art on such hydrogen storage materials, while trying to analyze the pros and cons of each material regarding its thermodynamic and kinetic behavior in hydrogenation studies

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years

Paving the Way to the Fuel of the Future&mdash;Nanostructured Complex Hydrides

Hydrides have emerged as strong candidates for energy storage applications and their study has attracted wide interest in both the academic and industry sectors. With clear advantages due to the solid-state storage of hydrogen, hydrides and in particular complex hydrides have the ability to tackle environmental pollution by offering the alternative of a clean energy source: hydrogen. However, several drawbacks have detracted this material from going mainstream, and some of these shortcomings have been addressed by nanostructuring/nanoconfinement strategies. With the enhancement of thermodynamic and/or kinetic behavior, nanosized complex hydrides (borohydrides and alanates) have recently conquered new estate in the hydrogen storage field. The current review aims to present the most recent results, many of which illustrate the feasibility of using complex hydrides for the generation of molecular hydrogen in conditions suitable for vehicular and stationary applications. Nanostructuring strategies, either in the pristine or nanoconfined state, coupled with a proper catalyst and the choice of host material can potentially yield a robust nanocomposite to reliably produce H2 in a reversible manner. The key element to tackle for current and future research efforts remains the reproducible means to store H2, which will build up towards a viable hydrogen economy goal. The most recent trends and future prospects will be presented herein

Graphene Supports for Metal Hydride and Energy Storage Applications

Energy production, distribution, and storage remain paramount to a variety of applications that reflect on our daily lives, from renewable energy systems, to electric vehicles and consumer electronics. Hydrogen is the sole element promising high energy, emission-free, and sustainable energy, and metal hydrides in particular have been investigated as promising materials for this purpose. While offering the highest gravimetric and volumetric hydrogen storage capacity of all known materials, metal hydrides are plagued by some serious deficiencies, such as poor kinetics, high activation energies that lead to high operating temperatures, poor recyclability, and/or stability, while environmental considerations related to the treatment of end-of-life fuel disposal are also of concern. A strategy to overcome these limitations is offered by nanotechnology, namely embedding reactive hydride compounds in nanosized supports such as graphene. Graphene is a 2D carbon material featuring unique mechanical, thermal, and electronic properties, which all recommend its use as the support for metal hydrides. With its high surface area, excellent mechanical strength, and thermal conductivity parameters, graphene can serve as the support for simple and complex hydrides as well as RHC (reactive hydride composites), producing nanocomposites with very attractive hydrogen storage properties

Recent Development in Nanoconfined Hydrides for Energy Storage

Hydrogen is the ultimate vector for a carbon-free, sustainable green-energy. While being the most promising candidate to serve this purpose, hydrogen inherits a series of characteristics making it particularly difficult to handle, store, transport and use in a safe manner. The researchers&rsquo; attention has thus shifted to storing hydrogen in its more manageable forms: the light metal hydrides and related derivatives (ammonia-borane, tetrahydridoborates/borohydrides, tetrahydridoaluminates/alanates or reactive hydride composites). Even then, the thermodynamic and kinetic behavior faces either too high energy barriers or sluggish kinetics (or both), and an efficient tool to overcome these issues is through nanoconfinement. Nanoconfined energy storage materials are the current state-of-the-art approach regarding hydrogen storage field, and the current review aims to summarize the most recent progress in this intriguing field. The latest reviews concerning H2 production and storage are discussed, and the shift from bulk to nanomaterials is described in the context of physical and chemical aspects of nanoconfinement effects in the obtained nanocomposites. The types of hosts used for hydrogen materials are divided in classes of substances, the mean of hydride inclusion in said hosts and the classes of hydrogen storage materials are presented with their most recent trends and future prospects

Crystal structure of catena-poly[[potassium-tri-μ-dimethylacetamide-κ6O:O] iodide]

The structure of catena-poly[[potassium-tri-μ-dimethylacetamide-κ6O:O] iodide], {[K(C4H9NO)3]I}n, at 120 K has trigonal (P-3) symmetry. The structure adopts a linear chain motif parallel to the crystallographic c axis. Two crystallographically independent K+ cations are present in the asymmetric unit located on threefold rotoinversion axes at [0, 0, 0] and [0, 0, 1/2] and are bridged by the O atoms of the acetamide moiety. This is an example of a rare μ2-bridging mode for dimethylacetamide O atoms. The iodide counter-ion resides on a threefold rotation axis in the channel formed by the [K(C4H9NO)]+ chains

C–H Activation Reactions of a Nucleophilic Palladium Carbene

The reactivity of a nucleophilic palladium carbene, [PC­(sp²)­P]­Pd­(PMe₃) (<b>1</b>; [PC­(sp²)­P] = bis­[2-(diisopropylphosphino)­phenyl]­methylene), toward the C–H bonds of CH₃COCH₃, CH₃CN, Ph–CCH, fluorene, and 9,10-dihydroanthracene was investigated. All surveyed substrates reacted with <b>1</b>. However, there was no detectable reaction of <b>1</b> with Ph₂CH₂. It is proposed that the p<i>K</i>_a values of the studied C–H bonds govern their reactivity toward <b>1</b>: our results show that substrates with a p<i>K</i>_a higher than 29, such as Ph₂CH₂ (p<i>K</i>_a = 32.2), do not react even with prolonged heating

C–H Activation Reactions of a Nucleophilic Palladium Carbene

The reactivity of a nucleophilic palladium carbene, [PC­(sp²)­P]­Pd­(PMe₃) (<b>1</b>; [PC­(sp²)­P] = bis­[2-(diisopropylphosphino)­phenyl]­methylene), toward the C–H bonds of CH₃COCH₃, CH₃CN, Ph–CCH, fluorene, and 9,10-dihydroanthracene was investigated. All surveyed substrates reacted with <b>1</b>. However, there was no detectable reaction of <b>1</b> with Ph₂CH₂. It is proposed that the p<i>K</i>_a values of the studied C–H bonds govern their reactivity toward <b>1</b>: our results show that substrates with a p<i>K</i>_a higher than 29, such as Ph₂CH₂ (p<i>K</i>_a = 32.2), do not react even with prolonged heating