Enhancing Metalating Efficiency of the Sodium Amide NaTMP in Arene Borylation Applications

Though LiTMP (TMP=2,2',6,6'-tetramethylpiperidide) is a commonly used amide, surprisingly the heavier NaTMP has hardly been utilised. Here, by mixing NaTMP with tridentate donor PMDETA (N,N,N',N'',N''-pentamethyldiethylenetriamine), we provide structural, and mechanistic insights into the sodiation of non-activated arenes (e.g. anisole and benzene). While these reactions are low yielding, adding B(OiPr)3 has a profound effect, not only by intercepting the CAr -Na bond, but also by driving the metalation reaction towards quantitative formation of more stabilized sodium aryl boronates. Demonstrating its metalating power, regioselective C2-metalation/borylation of naphthalene has been accomplished contrasting with single-metal based protocols which are unselective and low yielding. Extension to other arenes allows for in situ generation of aryl boronates which can then directly engage in Suzuki-Miyaura couplings, furnishing a range of biaryls in a selective and efficient manner

Uncovering the Untapped Potential of the Use of Sodium Amides for Regioselective Arene Functionalisation

Alkali-metal amides have become key reagents in synthetic chemistry, with special focus in deprotonation reactions. Despite the higher reactivity found in the heavier sodium and potassium amides, their insolubility and low stability has favoured the use of the more soluble  lithium analogues, converting them into the most used non-nucleophilic bases. Studying the coordination effects of Lewis donor molecules such as tridentate amine PMDETA (N,N,N’,N’’,N’’-pentamethyldiethylenetriamine) in combination with the sodium amide NaTMP (TMP = 2,2’,6,6’-tetramethylpiperidide), we have been able to unlock the use of these reagents for the functionalisation of arenes, i.e. the deuterium incorporation by hydrogen isotope exchange and the deprotonative borylation of unactivated arenes. These findings show how sodium amides are not just a simple more sustainable replacement of their lithium counterparts, but also that they can display significantly enhanced reactivities allowing for the development of new transformations

Sodium Mediated Deprotonative Borylation of Arenes Using Sterically Demanding B(CH2SiMe3)3: Unlocking Polybasic Behaviour and Competing Lateral Borane Sodiation

Producción CientíficaThe deprotonative metalation of organic molecules has become a convenient route to prepare functionalised aromatic substrates. Amongst the different metallating reagents available, sodium bases have recently emerged as a more sustainable and powerful alternative to their lithium analogues. Here we report the study of the sterically demanding electrophilic trap B(CH2SiMe3)3 for the deprotonative borylation of arenes using NaTMP (TMP = 2,2,6,6-tetramethylpiperidide) in combination with tridentate Lewis donor PMDETA (PMDETA = N,N,N′,N′′,N′′-pentamethyldiethylenetriamine). Using anisole and benzene as model substrates, unexpected polybasic behaviour has been uncovered, which enables the formal borylation of two equivalents of the relevant arene. The combination of X-ray crystallographic and NMR monitoring studies with DFT calculations has revealed that while the first B–C bond forming process takes place via a sodiation/borylation sequence to furnish [(PMDETA)NaB(Ar)(CH2SiMe3)3] (I) species, the second borylation step is facilitated by the formation of a borata-alkene intermediate, without the need of an external base. For non-activated benzene, it has aslo been found that under stoichimetric conditions the lateral sodiation of B(CH2SiMe3)3 becomes a competitive reaction pathway furnishing a novel borata-alkene complex. Showing a clear alkali-metal effect, the use of the sodium base is key to access this reactivity, while the metalation/borylation of the amine donor PMDETA is observed instead when LiTMP is usedUniversidad de Valladolid. Margarita Salas Postdoctoral Fellowship (CONVREC-2021-221)University of Bern and the Swiss National Science Foundation (Grant numbers 188573, 210608 and R'Equip 206021_177033)The Irish Research Council (M.M. GOIPG/2021/88

Nickel-Catalyzed Reductive Carboxylation and Amidation of Organic Matter

En els darrers anys, el desenvolupament de reaccions de carboxilació reductiva de (pseudo) halogenurs orgànics amb diòxid de carboni (CO") catalitzada per metalls per a la preparació d'àcids carboxílics s'ha convertit en una poderosa alternativa a l'ús d'èspecies organometàl·liques, en la majoria dels casos sensibles a l'aire. Tanmateix, l'ús d'alcohols simples no protegits o d'hidrocarburs insaturats en combinació amb CO" per obtenir àcids carboxílics mitjançant una reacció de formació d'un enllaç C-C han rebut molta menys atenció. Aquests representen una alternativa atractiva als halurs orgànics, ja que són abundants i fàcilment disponibles. En aquesta tesi doctoral es descriu la carboxilació selectiva d'alcohols al·lílics amb CO2, una metodologia capaç d'obtenir àcids carboxílics insaturats amb un control excel·lent de la selectivitat obtinguda

Alkali-metal bases in catalytic hydrogen isotope exchange processes

he preparation of compounds labelled with deuterium or tritium has become an essential tool in a range of research fields. Hydrogen isotope exchange (HIE) offers direct access to said compounds, introducing these isotopes in a late stage. Even though the field has rapidly advanced with the use of transition metal catalysis, alkali-metal bases, used as catalysts or under stoichiometric conditions, have also emerged as a viable alternative. In this minireview we describe the latest advances in the use of alkali-metal bases in HIE processes, showcasing their synthetic potential as well as current challenges in the field. It is divided in different sections based on the isotope source used, emphasizing their benefits, disadvantages and limitations. The influence on the choice of alkali-metal in these processes as well as their possible mechanistic pathways are also discussed

Directiva INSPIRE: anàlisi de la directiva i de les ferramentes cooperatives per a la correcta creació d informació geogràfica

[CA] El present document es crea amb la finalitat d’apropar als professionals de la geomàtica, així com d’altres àmbits (medi ambient, urbanisme, etc.), els avantatges i les facilitats per crear i compartir noves dades d’informació geogràfica dins la Unió Europea, gràcies a l’aplicació de la Directiva INSPIRE. El treball consta de dues parts clarament diferenciades. Mentre que en la primera, es farà un estudi dels capítols i articles que conformen aquesta Directiva europea per conéixer-la i entendre la seua finalitat, en la segona s’analitzaran les ferramentes que fan més fàcil la creació d’aquestes dades, a causa del treball cooperatiu entre professionals de diferents camps i països.[EN] This document is created with the aim of bringing together professionals in geomatics and related fields (environment, urban planning, etc. ), the advantages for creating and sharing new geographical information data in European Union thanks to the implementation of the INSPIRE Directive. This project consists of two differentiated parts. While the first part will focus on the understanding of the purpose of the Directive through a study of its chapters and articles, the second part will analyse the tools that facilitate the generation of data through cooperative work between professionals from different fields and countries.[ES] El presente documento se crea con el fin de acercar a los profesionales de la geomática, así como otros ámbitos (medio ambiente, urbanismo, etc.), las ventajas y las facilidades para crear y compartir nuevos datos de información geográfica dentro de la Unión Europea, gracias a la aplicación de la Directiva INSPIRE. El trabajo consta de dos partes claramente diferenciadas. Mientras que en la primera, se hará un estudio de los capítulos y artículos que conforman esta Directiva europea para conocerla y entender su finalidad, en la segunda se analizarán las herramientas que hacen más fácil la creación de estos datos, debido al trabajo cooperativo entre profesionales de diferentes campos y países.Pedrola Tortajada, A. (2019). Directiva INSPIRE: anàlisi de la directiva i de les ferramentes cooperatives per a la correcta creació d informació geogràfica. Universitat Politècnica de València. http://hdl.handle.net/10251/133688TFG