ABSTRACT
Gold catalysis has emerged as a groundbreaking field in synthetic chemistry, revolutionizing numerous organic transformations. Despite the significant achieved advancements, the mechanistic understanding behind many gold-catalyzed reactions remains elusive. This Concept article covers the so-called "self-activating" Au(I) complexes, sorting out their pivotal role in gold catalysis. We comment on how Au(I) complexes can undergo self-activation, triggering diverse catalytic transformations without the need for external additives. The most important examples reported so far that underlie the catalytic activity of these species are discussed. This intrinsic reactivity represents a paradigm shift in gold catalysis, offering new avenues for the design of efficient and sustainable catalytic systems. Furthermore, we explore the factors influencing the stability, reactivity, and selectivity of these Au(I) complexes, providing insights into their synthetic utility and potential applications. This area of research not only advances our fundamental understanding of gold catalysis but also paves the way for the development of novel catalytic strategies with broad implications in organic synthesis and the chemical industry.
ABSTRACT
Invited for the cover of this issue are the groups of Raquelâ P. Herrera and M.â Concepción Gimeno at the Instituto de Síntesis Química y Catálisis Homogénea (University of Zaragoza-CSIC). The image depicts the light of the full moon illuminating a bridge between the gold(I) metal centers. Two dragons, symbolizing the use of bridging ligands, confront each other to determine the ultimate victor. Read the full text of the article at 10.1002/chem.202303585.
ABSTRACT
Gold(II) complexes, unlike their gold(I) and gold(III) counterparts, have been sparsely employed in the field of catalysis. This is primarily due to the challenges associated with isolating and characterising these open-shell species. However, these complexes offer a wide range of possibilities. On one hand, this intermediate oxidation state has proven to be more easily accessible through reduction and oxidation processes compared to the gold(I)/gold(III) redox couple, thereby facilitating potential homo-coupling and cross-coupling reactions. On the other hand, gold(II) exhibits Lewis acid behaviour, bridging the characteristics of the soft acid gold(I) and the hard acid gold(III). In this review, we focus on mono- and dinuclear gold(II) complexes, whether they are isolated and well-studied or proposed as intermediates in cross-coupling reactions induced by the action of oxidants or light. We delve into the unique reactivity and potential applications of these gold(II) species, shedding light on their role in this field. This comprehensive exploration aims to underscore the latent promise of gold(II) complexes in catalysis, offering insights into their structural and mechanistic aspects while highlighting their relevance in contemporary chemical transformations.
ABSTRACT
The combination of the ferrocene moiety with gold(I) catalysis remains a relatively unexplored field. In this article, we delve into the synthesis, characterization, and potential catalytic activity of four complexes utilizing both monodentate and bidentate ferrocenyl diphenylphosphane ligands (ppf and dppf), coordinated with two gold(I) metal centers, linked by either chloride or pentafluorophenylthiolate bridging ligands. This leads to the formation of cationic "self-activated" precatalysts capable of initiating the catalytic cycle without the need for external additives. The catalytic activity of these complexes was assessed through a model reaction in gold(I) catalysis, specifically the cyclization of a N-propargylbenzamide to produce an oxazole. In addition, we studied and compared the influence exerted by both the phosphane and the bridging ligand on the performance of these catalysts.
ABSTRACT
El sustituto sanguíneo ideal es aquel que logra reponer volumen y a la vez tiene la capacidad de transportar de oxígeno. Actualmente existen sustancias que tienen una u otra cualidad y algunas podrían tener ambas; como las soluciones de hemoglobina y las emulsiones de perfluorocarbonados que aún se encuentran en estudio. Así, también se han utilizado tratamientos farmacológicos que funcionan profilácticamente para evitar el sangrado o tratar anemias severas sin recurrir al uso de transfusiones sanguíneas. Se presenta una revisión sobre estos temas y algunos puntos de vista controversiales sobre las transfusiones sanguíneas.
