Catalytic addition of C–H bonds across C–C unsaturated systems promoted by iridium(i) and its group IX congeners

Transition metal-catalyzed hydrocarbonations of unsaturated substrates have emerged as powerful synthetic tools for increasing molecular complexity in an atom-economical manner. Although this field was traditionally dominated by low valent rhodium and ruthenium catalysts, in recent years, there have been many reports based on the use of iridium complexes. In many cases, these reactions have a different course from those of their rhodium homologs, and even allow performing otherwise inviable transformations. In this review we aim to provide an informative journey, from the early pioneering examples in the field, most of them based on other metals than iridium, to the most recent transformations catalyzed by designed Ir(I) complexes. The review is organized by the type of C–H bond that is activated (with C sp2, sp or sp3), as well as by the C–C unsaturated partner that is used as a hydrocarbonation partner (alkyne, allene or alkene). Importantly, we discuss the mechanistic foundations of the methods highlighting the differences from those previously proposed for processes catalyzed by related metals, particularly those of the same group (Co and Rh)This work received financial support from Spanish grants (SAF2016-76689-R, CTQ2016-77047-P, CTQ2017-84767-P and ORFEO-CINQA network CTQ2016-81797-REDC), the Consellería de Cultura, Educación e Ordenación Universitaria (2015-CP082, ED431C-2017/19 and Centro Singular de Investigación de Galicia accreditation 2019–2022, ED431G 2019/03), the European Union (European Regional Development Fund-ERDF corresponding to the multiannual financial framework 2014–2020), and the European Research Council (Advanced Grant No. 340055). DFF thanks Xunta de Galicia for his postdoctoral fellowship (ED481B-2019-005)S

Sparse and random sampling techniques for high-resolution, full-field, bss-based structural dynamics identification from video

Video-based techniques for identification of structural dynamics have the advantage that they are very inexpensive to deploy compared to conventional accelerometer or strain gauge techniques. When structural dynamics from video is accomplished using full-field, high-resolution analysis techniques utilizing algorithms on the pixel time series such as principal components analysis and solutions to blind source separation the added benefit of high-resolution, full-field modal identification is achieved. An important property of video of vibrating structures is that it is particularly sparse. Typically video of vibrating structures has a dimensionality consisting of many thousands or even millions of pixels and hundreds to thousands of frames. However the motion of the vibrating structure can be described using only a few mode shapes and their associated time series. As a result, emerging techniques for sparse and random sampling such as compressive sensing should be applicable to performing modal identification on video. This work presents how full-field, high-resolution, structural dynamics identification frameworks can be coupled with compressive sampling. The techniques described in this work are demonstrated to be able to recover mode shapes from experimental video of vibrating structures when 70% to 90% of the frames from a video captured in the conventional manner are removed

Rhodium(III)-Catalyzed Intramolecular Annulations of Acrylic and Benzoic Acids to Alkynes

Rh(III) catalysts can promote a formal (4 + 2) intramolecular oxidative annulation between acrylic or benzoic acid derivatives and alkynes. The reaction, which involves a C–H activation process, allows for a rapid assembly of appealing bicyclic pyran-2-ones and tricyclic isocoumarin derivatives in moderate to good yields. The α-pyrone moiety of the products provides for further manipulations to obtain relatively complex cyclic skeletons in a very simple mannerThis work has received financial support from Spanish grants (SAF2016-76689-R, CTQ2016-77047-P, and FPI fellowship to D.F.F.), the Consellería de Cultura, Educación e Ordenación Universitaria (ED431C 2017/19, 2015-CP082, and Centro Singular de Investigación de Galicia acreditación 2016-2019, ED431G/09), the European Regional Development Fund (ERDF), and the European Research Council (Advanced Grant no. 340055). The orfeo-cinqa network CTQ2016-81797-REDC is also kindly acknowledgedS

Spatiotemporal video-domain high-fidelity simulation and realistic visualization of full‐field dynamic responses of structures by a combination of high-spatial-resolution modal model and video motion manipulations

Structures with complex geometries, material properties, and boundary conditions exhibit spatially local dynamic behaviors. A high‐spatial‐resolution model of the structure is thus required for high‐fidelity analysis, assessment, and prediction of the dynamic phenomena of the structure. The traditional approach is to build a highly refined finite element computer model for simulating and analyzing the structural dynamic phenomena based on detailed knowledge and explicit modeling of the structural physics such as geometries, materials properties, and boundary conditions. These physics information of the structure may not be available or accurately modeled in many cases, however. In addition, the simulation on the high‐spatial‐resolution structural model, with a massive number of degrees of freedom and system parameters, is computationally demanding. This study, on a proof‐of‐principle basis, proposes a novel alternative approach for spatiotemporal video‐domain high‐fidelity simulation and realistic visualization of full‐field structural dynamics by an innovative combination of the fundamentals of structural dynamic modeling and the advanced video motion manipulation techniques. Specifically, a low‐modal‐dimensional yet high‐spatial (pixel)‐resolution (as many spatial points as the pixel number on the structure in the video frame) modal model is established in the spatiotemporal video domain with full‐field modal parameters first estimated from line‐of‐sight video measurements of the operating structure. Then in order to simulate new dynamic response of the structure subject to a new force, the force is projected onto each modal domain, and the modal response is computed by solving each individual single‐degree‐of‐freedom system in the modal domain. The simulated modal responses are then synthesized by the full‐field mode shapes using modal superposition to obtain the simulated full‐field structural dynamic response. Finally, the simulated structural dynamic response is embedded into the original video, replacing the original motion of the video, thus generating a new photo‐realistic, physically accurate video that enables a realistic, high‐fidelity visualization/animation of the simulated full‐field vibration of the structure. Laboratory experiments are conducted to validate the proposed method, and the error sources and limitations in practical implementations are also discussed. Compared with high‐fidelity finite element computer model simulations of structural dynamics, the video‐based simulation method removes the need to explicitly model the structure's physics. In addition, the photo‐realistic, physically accurate simulated video provides a realistic visualization/animation of the full‐field structural dynamic response, which was not traditionally available. These features of the proposed method should enable a new alternative to the traditional computer‐aided finite element model simulation for high‐fidelity simulating and realistically visualizing full‐field structural dynamics in a relatively efficient and user‐friendly manner

Gold(I)–catalyzed enantioselective annulations between allenes and alkene-tethered oxime ethers: A straight entry to highly substituted piperidines and aza-bridged medium-sized carbocycles

NOTICE: This is the peer reviewed version of the following article: Marcote, D. C., Varela, I., Fernández-Casado, J., Mascareñas, J.L., López*, F. (2019), Gold(I)–catalyzed enantioselective annulations between allenes and alkene-tethered oxime ethers: A straight entry to highly substituted piperidines and aza-bridged medium-sized carbocycles. J. Am. Chem. Soc., 140, 16821-16833 [doi: 10.1021/jacs.8b10388]. This article may be used for non-commercial purposes in accordance with ACS Terms and Conditions for self-archivingPiperidine scaffolds are present in a wide range of bioactive natural products and are therefore considered as highly valuable, privileged synthetic targets. In this manuscript, we describe a gold-catalyzed annulation strategy that allows a straightforward assembly of piperidines and piperidine-containing aza-bridged products from readily available alkene-tethered oxime ethers (or esters) and N-allenamides. Importantly, we demonstrate the advantages of using oxime derivatives over imines, something pertinent to the whole area of gold catalysis, and provide relevant mechanistic experiments that shed light into the factors affecting the annulation processes. Moreover, we also describe preliminary experiments demonstrating the viability of enantioselective versions of the above reactionsThis work received financial support from the Spanish MINECO (SAF2016-76689-R, CTQ2017-84767-P, FPU fellowship to I.V. and J.F.-C.), the Xunta de Galicia (ED431C 2017/19, 2015-CP082, Centro Singular de Investigacion de Galicia accreditation 2016-2019 ED431G/09 and ́ predoctoral fellowship to D.C.M.), the ERDF, ERC (Adv. Grant No. 340055), and the Orfeo-Cinqa network (CTQ2016- 81797-REDC). Dr. Rebeca Garcí a-Fandiño is acknowledged for her contribution to the DFT studiesS

DNA-binding miniproteins based on zinc fingers. Assessment of the interaction using nanopores

Obtaining artificial proteins that mimic the DNA binding properties of natural transcription factors could open new ways of manipulating gene expression at will. In this context it is particularly interesting to develop simple synthetic systems. Inspired by the modularity of natural transcription factors, we have designed synthetic miniproteins that combine the zinc finger module of the transcription factor GAGA and AT-hook peptide domains. These constructs are capable of binding to composite DNA sequences of up to 14 base pairs with high affinity and good selectivity. In particular, we have synthesized three different chimeras and characterized their DNA binding properties by electrophoresis and fluorescence anisotropy. We have also used, for the first time in the study of peptide-based DNA binders, nanopore force spectroscopy to obtain further data on the DNA interaction

Highly Enantioselective Iridium(I)-Catalyzed Hydrocarbonation of Alkenes: A Versatile Approach to Heterocyclic Systems Bearing Quaternary Stereocenters

We report a versatile, highly enantioselective intramolecular hydrocarbonation reaction that provides a direct access to heteropolycyclic systems bearing chiral quaternary carbon stereocenters. The method, which relies on an iridium(I)/bisphosphine chiral catalyst, is particularly efficient for the synthesis of five-, six- and seven-membered fused indole and pyrrole products, bearing one and two stereocenters, with enantiomeric excesses of up to >99 %. DFT computational studies allowed to obtain a detailed mechanistic profile and identify a cluster of weak non-covalent interactions as key factors to control the enantioselectivityThis work received financial support from the Spanish MINECO (SAF2016-76689-R, PID2019-108624RB-I00, CTQ2017-84767-P, PID2020-118579GB-I00), the Xunta de Galicia (ED431C 2017/19, 2015-CP082, Centro Singular de Investigación de Galicia accreditation 2019-2022, ED431G 2019/03, a predoctoral Fellowship to A. A. and M. C. and a postdoctoral Fellowship to D. F. F, ED481B-2019-005) and the ERDF, ERC (Adv. Grant No. 340055). The Orfeo-Cinqa network (CTQ2016-81797-REDC)S

Iridium(I)-Catalyzed Intramolecular Cycloisomerization of Enynes: Scope and Mechanistic Course

NOTICE: This is the peer reviewed version of the following article: David F. Fernández, Catarina A. B. Rodrigues, Martín Calvelo, Moisés Gulías, José L. Mascareñas and Fernando López (2018), Iridium(I)-Catalyzed Intramolecular Cycloisomerization of Enynes: Scope and Mechanistic Course. ACS Catalysis, 2018, 8 (8), 7397–7402 [DOI: 10.1021/acscatal.8b02139]. This article may be used for non-commercial purposes in accordance with American Chemical Society Terms and Conditions for self-archivingWe report an Ir(I)-catalyzed cycloisomerization methodology that provides access to carbocyclic systems bearing exo-alkene moieties from alkynyl-equipped acyclic precursors. The method relies on the C–H activation of olefinic and (hetero)aromatic C(sp2)–H bonds, followed by an exocyclization to a tethered alkyne, and provides interesting cyclic diene products that are amenable of further elaboration. Importantly, DFT calculations suggests that, in contrast to related hydrocarbonations of alkenes in which either migratory insertions or C–C reductive eliminations have been suggested to be rate-determining, in our reactions, the energetic barrier of these steps is lower than that of the previous C–H activationThis work received financial support from the Spanish MINECO (Nos. SAF2016-76689-R, CTQ2016-77047-P, and CTQ2017-84767-P, as well as an FPI fellowship to D.F.F.), the Xunta de Galicia (Nos. ED431C 2017/19 and 2015-CP082, as well as Centro Singular de Investigación de Galicia accreditation 2016-2019 ED431G/09 and predoctoral fellowship to M.C.), the ERDF, ERC (Adv. Grant No. 340055) and the Orfeo-Cinqa network (No. CTQ2016-81797-REDC). Dr. Rebeca García-Fandiño is acknowledged for helpful suggestions on DFT studiesS

Spatiotemporal video-domain high-fidelity simulation and realistic visualization of full‐field dynamic responses of structures by a combination of high-spatial-resolution modal model and video motion manipulations

Structures with complex geometries, material properties, and boundary conditions exhibit spatially local dynamic behaviors. A high‐spatial‐resolution model of the structure is thus required for high‐fidelity analysis, assessment, and prediction of the dynamic phenomena of the structure. The traditional approach is to build a highly refined finite element computer model for simulating and analyzing the structural dynamic phenomena based on detailed knowledge and explicit modeling of the structural physics such as geometries, materials properties, and boundary conditions. These physics information of the structure may not be available or accurately modeled in many cases, however. In addition, the simulation on the high‐spatial‐resolution structural model, with a massive number of degrees of freedom and system parameters, is computationally demanding. This study, on a proof‐of‐principle basis, proposes a novel alternative approach for spatiotemporal video‐domain high‐fidelity simulation and realistic visualization of full‐field structural dynamics by an innovative combination of the fundamentals of structural dynamic modeling and the advanced video motion manipulation techniques. Specifically, a low‐modal‐dimensional yet high‐spatial (pixel)‐resolution (as many spatial points as the pixel number on the structure in the video frame) modal model is established in the spatiotemporal video domain with full‐field modal parameters first estimated from line‐of‐sight video measurements of the operating structure. Then in order to simulate new dynamic response of the structure subject to a new force, the force is projected onto each modal domain, and the modal response is computed by solving each individual single‐degree‐of‐freedom system in the modal domain. The simulated modal responses are then synthesized by the full‐field mode shapes using modal superposition to obtain the simulated full‐field structural dynamic response. Finally, the simulated structural dynamic response is embedded into the original video, replacing the original motion of the video, thus generating a new photo‐realistic, physically accurate video that enables a realistic, high‐fidelity visualization/animation of the simulated full‐field vibration of the structure. Laboratory experiments are conducted to validate the proposed method, and the error sources and limitations in practical implementations are also discussed. Compared with high‐fidelity finite element computer model simulations of structural dynamics, the video‐based simulation method removes the need to explicitly model the structure's physics. In addition, the photo‐realistic, physically accurate simulated video provides a realistic visualization/animation of the full‐field structural dynamic response, which was not traditionally available. These features of the proposed method should enable a new alternative to the traditional computer‐aided finite element model simulation for high‐fidelity simulating and realistically visualizing full‐field structural dynamics in a relatively efficient and user‐friendly manner