Copper‐Catalyzed Selective Pyrrole Functionalization by Carbene Transfer Reaction

1H‐Pyrroles can be directly functionalized by means of the incorporation of carbene groups from diazo compounds, in a process catalyzed by TpxCu complexes (Tpx=hydrotrispyrazolylborate ligand). The reactions take place with a complete selectivity toward the formal insertion of the carbene into the Cα−H bond, leading to alkylated pyrroles, with no modification of the Cβ−H, N−H or C=C bonds of the pyrrole unit. Alkyl substituents at C‐ring as well as alkyl, aryl, allyl or alkyne substitution at N atom are tolerated, the strategy affording 20 new pyrrole derivatives. The observance of partial deuteration at the methylene group when the reaction is carried out with added D2O serves to discard the direct insertion of the carbene group into the Csp2−H bond, the alternative electrophilic attack to the pyrrole ring being feasible.Support for this work was provided by the MINECO (CTQ2017- 82893-C2-1-R and PO FEDER 2014-2020, UHU-1254043). AMR thanks MINECO for a FPU fellowship

Pyrrole Functionalization by Copper‐Catalyzed Nitrene Transfer Reactions

The catalytic functionalization of pyrroles by incorporation of a nitrene group is reported. The Cα‐H bond of 1H‐pyrrole is amidated upon the formal insertion of the NTs (Ts=p‐toluenesulfonyl) group catalyzed by TpBr3Cu(NCMe) (TpBr3=hydrotris(3,4,5‐tribromo‐pyrazolyl)borate). N‐substituted pyrroles also verify the same transformation. The mechanism proposal is similar to that previously described for benzene amidation with the same catalyst and PhI=NTs, which takes place through aziridine formation, ring opening and 1,2‐hydrogen shift. A cascade reaction involving the coupling of 2,5‐dimethylfuran, 1,2,3‐trimethyl‐pyrrole and a nitrene NTs group is also described, leading to a 1,2‐dihydropyridine‐imine compound.Support for this work was provided by the MINECO (CTQ2017‐82893‐C2‐1‐R and PO FEDER 2014‐2020, UHU‐1254043). AMR and MRR thanks MEC for a FPU fellowships

Determining optimal flight paths for cellular network connectivity for the transmission of real-time physiological data in support of big data analytics during airborne critical care transport

This thesis presents a methodology for determining the optimal flight paths between two geographical points based on distance and cellular reception over the path. This methodology consists of two main concepts: coverage map generation, and path planning. Coverage map generation creates a grid map of the total planning space that contains coverage information for each grid point. Coverage is calculated based on geographical and technical information regarding each cell tower in the planning area. The planning step utilises the coverage map to plan a route based on minimum distance and maximum coverage, which is then smoothed into a feasible route for an aircraft to follow. This methodology is demonstrated in an airborne critical care transport within the Province of Ontario in Canada context. Leveraging available cellular information, this methodology is used to determine optimal paths between various care centres or their closest airport. Evaluation reveals that optimal routes can be found through this methodology

Introducing Fe and Mn as catalysts for the selective functionalization of Csp2-H bonds of arenes by carbene insertion

Título de la versión post-print: Introducing Fe and Mn as catalysts for the selective functionalization of Csp2-H bonds of arenes by carbene insertionThe first examples of the direct functionalization of non-activated aryl sp(2) C-H bonds with ethyl diazoacetate (N2CHCO2Et) catalyzed by Mn- or Fe-based complexes in a completely selective manner are reported, with no formation of the frequently observed cycloheptatriene derivatives through competing Buchner reaction. The best catalysts are Fe-II or Mn-II complexes bearing the tetradentate pytacn ligand (pytacn = 1-(2-pyridylmethyl)-4,7-dimethyl-1,4,7-triazacyclononane). When using alkylbenzenes, the alkylic C(sp(3))-H bonds of the substituents remained unmodified, thus the reaction being also selective toward functionalization of sp(2) C-H bonds.Support for this work was provided by the MINECO (CTQ2014-52769-C3-R-1, CTQ2014-62234-EXP, CTQ2015-70795-P, CTQ2014-54306-P, and CTQ2014-52525P), and the Junta de Andalucia (P10-FQM-06292). A.C. thanks Junta de Andalucia for a research contract. M.C. acknowledges an ICREA Academia Award, 2014 SGR 862 from Generalitat de Catalunya, and ERC-239910

Introducing the Catalytic Amination of Silanes via Nitrene Insertion

The direct functionalization of Si−H bonds by the nitrene insertion methodology is described. A copper(I) complex bearing a trispyrazolylborate ligand catalyzes the transfer of a nitrene group from PhINTs to the Si−H bond of silanes, disilanes, and siloxanes, leading to the exclusive formation of Si−NH moieties in the first example of this transformation. The process tolerates other functionalities in the substrate such as several C−H bonds and alkyne and alkene moieties directly bonded to the silicon center. Density functional theory (DFT) calculations provide a mechanistic interpretation consisting of a Si−H homolytic cleavage and subsequent rebound to the Si-centered radical.We thank the Ministerio de Ciencia e Innovación for Grants PID2020-113797RB-C21, PID2020-112825RB-I00, and CEX2019-000925-S as well as FEDER for “Una manera de hacer Europa” funding. We also thank Junta de Andalucía (P20-00348) and Universidad de Huelva (P.O.Feder UHU202016). A.M.R. and R.P.-S. thank Ministerio de Universidades for the FPU fellowships (FPU17/02738 and FPU18/ 01138, respectively), and J.P.-R. thanks Fondo de Garantía Juvenil for a research contract. CERCA Programme/Generalitat de Catalunya is also acknowledged. We thank Prof. T. R. Belderrain for helpful discussions on 29Si NMR spectroscopy. Funding for open access charge: Universidad de Huelva / CBU

Gold-catalyzed naphthalene functionalization

The complexes IPrMCl (IPr = 1,3-bis(diisopropylphenyl)imidazol-2-ylidene, M = Cu, 1a; M = Au, 1b), in the presence of one equiv of NaBAr'4 (Ar' = 3,5-bis(trifluoromethyl)phenyl), catalyze the transfer of carbene groups: C(R)CO2Et (R = H, Me) from N2C(R)CO2Et to afford products that depend on the nature of the metal center. The copper-based catalyst yields exclusively a cycloheptatriene derivative from the Buchner reaction, whereas the gold analog affords a mixture of products derived either from the formal insertion of the carbene unit into the aromatic C–H bond or from its addition to a double bond. In addition, no byproducts derived from carbene coupling were observed

Evidencing an inner-sphere mechanism for NHC-Au(I)-catalyzed carbene-transfer reactions from ethyl diazoacetate

Kinetic experiments based on the measurement of nitrogen evolution in the reaction of ethyl diazoacetate (N2CHCO2Et, EDA) and styrene or methanol catalyzed by the [IPrAu]+ core (IPr = 1,3-bis(diisopropylphenyl)imidazole-2-ylidene) have provided evidence that the transfer of the carbene group CHCO2Et to the substrate (styrene or methanol) takes place in the coordination sphere of Au(I) by means of an inner-sphere mechanism, in contrast to the generally accepted proposal of outer-sphere mechanisms for Au(I)-catalyzed reactions

Selective Synthesis of N-Substituted 1,2-Dihydropyridines from Furans by Copper-Induced Concurrent Tandem Catalysis

8 páginas, 4 figuras, 1 tabla, 9 esquemasA novel transformation in which mono- or dialkyl-substituted furans are converted into 1,2-dihydropyridines upon reaction with PhI═NTs at room temperature is reported. The reaction is catalyzed by complexes of general formula TpxM (M = Cu, Ag) and consists of a one-pot procedure with four consecutive catalytic cycles. Furan aziridination is followed by aziridine ring-opening, transimination reaction, inverse-electronic-demand aza-Diels−Alder reaction, and a final hydrogen elimination reaction. The mechanism of the overall transformation is proposed where the metal complex displays a crucial role along the reaction pathway.Financial support of this work by MEC (CTQ2008-00042/BQU and Consolider Ingenio 2010, Grant No. CSD2006-0003) is acknowledged.Peer reviewe