Recent HOCA contribution to the field of Deep Eutectic Solvents

Posted on February 16, 2024 by mmaamarq

L-Proline-based deep eutectic solvents as green and enantioselective organocatalyst/media for aldol reaction, Zárate-Rondán, S.; Trujillo-Rodríguez, M. J.; Gimeno, M. C.; Herrera, R. P. J. Mol. Liq. 2024, 396, 123971. DOI: 10.1016/j.molliq.2024.123971.

Abstract

The use of chiral deep eutectic solvents (DESs) based on the natural amino acid L-proline and various glycols presents an environmentally friendly approach for important Csingle bondC bond formation reactions. These DESs serve as both organocatalysts and reaction media in the aldol reaction, reducing the need for additional toxic or hazardous chemicals. By employing these DESs, we were able to activate the desired reaction through the condensation of ketones and L-proline via enamine activation. This approach eliminates the requirement for traditional, often environmentally harmful, organic solvents. Notably, diethylene glycol played a crucial role in modulating the reaction performance, including conversion and enantioselectivity. Diethylene glycol is a relatively safer alternative compared to other commonly used solvents or additives with potential environmental and health risks. Moreover, reducing the L-proline content in the DESs led to a slight increase in the enantiomeric excess of the predominant diastereomeric product. This finding suggests the possibility of minimizing the use of L-proline, which can be advantageous from both cost and environmental perspectives.

The results of these reactions demonstrate promising green outcomes, with a diastereomeric ratio up to 25:1 for the major anti-isomer, showcasing excellent selectivity (>90 % ee). In addition to these high enantiomeric excess values, quantitative yields in the aldol reaction highlight the potential for high efficiency and reduced waste production.

Overall, the utilization of chiral DESs based on L-proline and glycols offers a greener alternative for enantioselective organocatalytic reactions. This approach minimizes the use of hazardous catalysts, reduces waste generation, and demonstrates impressive selectivity, paving the way for more sustainable synthetic methodologies.

Posted in Publication, Research | Tagged , , , , , , , , | Leave a comment

Starting the New Year in a good mood!

Posted on January 8, 2024 by mmaamarq

Two new works already publicated in 2024. Congratulations!

Ferrocenyl Dinuclear Gold(I) Complexes. Study of their Structural Features and the Influence of Bridging and Phosphane Ligands in a Catalytic Cyclization Reaction, Pérez-Sánchez, J. C.; Herrera, R. P.; Gimeno, M. C. Chem. Eur. J. 2024, accepted. DOI: 10.1002/chem.202303585. 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.

Unlocking the Catalytic Potential of Gold(II) Complexes: A Comprehensive Reassessment, Pérez-Sánchez, J. C.; Herrera, R. P.; Gimeno, M. C. Dalton Trans. 2024, 53, 382-393. DOI: 10.1039/D3DT03687A. 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.

Posted in Publication, Raquel P. Herrera | Tagged , , , , , , , | Leave a comment

Merry Christmas and Happy New Year 2024!

Posted on December 23, 2023 by mmaamarq
Posted in Fun | Tagged , , , | Leave a comment

Enjoy our new Cover in Adv. Synth. Catal.

Posted on October 16, 2023 by mmaamarq

Just published our new cover that illustrates our recent article on Asymmetric Organocatalyzed Phospha-Michael Addition for the Direct Synthesis of Biologically Active Chromenylphosphonates.

The inside cover picture is an artistic illustration of the bifunctional activation of the phosphite and the iminochromene by a chiral squaramide tattooed on the arm of a chemist. Both substrates undergo the phospha-Michael reaction described in the original article, enabling the chemist to have in hand enantioenriched chromenylphosphonates, an interesting family of bioactive compounds. The cover design is by I. G. Sonsona. Details can be found in the communication by Marqués-López and Herrera and co-workers (E. Marqués-López, I. G. Sonsona, M. Garcés-Marín, M. C. Gimeno, R. P. Herrera, Adv. Synth. Catal. 2023, 365, 3234–3240; DOI: 10.1002/adsc.202300563. Special Issue in Chem. Asian J.: Hot Topic: Organocatalysis).

Posted in Publication | Tagged , , , , , , , , , , , | Leave a comment

Paper 100 in our web of “Recent publications”

Posted on September 4, 2023 by mmaamarq

Unravelling the role of triisopropylphosphane telluride in Ag(I) complexes,   Pérez-Sánchez, J. C..; Ceamanos, C.; Herrera, R. P.; Gimeno, M. C. Inorg. Chem. Front. 2023, 365. DOI: 10.1039/D3QI01485A.

Abstract. The coordination chemistry of chalcogenide ligands has always attracted significant interest in the field of inorganic chemistry, especially for soft metals such as those of group 11. Despite the scarcity of research on phosphane tellurides, we report on the synthesis and characterisation of five novel silver complexes containing the phosphane telluride ligand, TeP(iPr)3, along with other ancillary ligands such as mono or diphosphanes. Spectroscopic studies were performed to investigate the behaviour of these complexes, including their redox properties, as demonstrated by the 1,1′-diphenylphosphaneferrocene (dppf) silver derivatives. Additionally, these complexes showcase remarkable rapid interchange equilibrium, revealing silver species with distinctive Ag2Te2 cores and a combination of bridging and terminal TeP(iPr)3 ligands. A promising avenue for further investigation and potential applications emerges.

Congratulations!!

Posted in Publication | Tagged , , , , , | Leave a comment

Smooth synthesis of chromenylphosphonates, early view

Posted on August 17, 2023 by mmaamarq

Asymmetric Organocatalyzed Phospha-Michael Addition for the Direct Synthesis of Biologically Active Chromenylphosphonates,*   Marqués-López, E.; Sonsona, I. G.; Garcés-Marín, M.; Gimeno, M. C.; Herrera, R. P. Adv. Synth. Catal. 2023, 365. DOI: 10.1002/adsc.202300563. *A previous version of this manuscript has been deposited on a preprint server (DOI: 10.26434/chemrxiv-2023-dpm20).

Abstract. The potential of phosphites as nucleophiles for the asymmetric synthesis of chiral chromene derivatives has been overlooked in the literature. Herein, we report a promising approach via asymmetric organocatalyzed phospha-Michael addition to iminochromenes, using a bifunctional squaramide, which gives access to chromenylphosphonates, an interesting family of bioactive compounds. Our optimized protocol provides very good reactivity, affording yields of up to 95% and with chiral products exhibiting an enantiomeric excess of up to 98%.

Congratulation and thank you very much!!

Posted in Chromene, Eugenia Marqués-López, Heterocycle, Organocatalysis, Publication, Raquel P. Herrera, Research | Tagged , , , , , , , , , , , | Leave a comment

A nice work, just published in Hot Topic: C-H Activation

Posted on July 18, 2023 by mmaamarq

Enantioselective C−P Bond Formation through C(sp3)−H Functionalization,*   Ardevines, S.; Horn, D.; Alegre-Retquena, J. V.; González-Jiménez, M.; Gimeno, M. C.; Marqués-López, E.; Herrera, R. P. Adv. Synth. Catal. 2023, 365, 2152–2158. DOI: 10.1002/adsc.202300393. *A previous version of this manuscript has been deposited on a preprint server (DOI: 10.26434/chemrxiv-2023-v3vl0).

Congratulations and thanks to everyone!

Abstract. An enantioselective C−P bond formation has been developed through a C(sp3)−H activation in an oxidation step followed by an organocatalyzed hydrophosphonylation protocol. The asymmetric organocatalytic Pudovik reaction has been achieved following a one-pot strategy, starting from different benzylic and allylic alcohols and dibenzyl phosphite, using MnO2 as the oxidant and a chiral squaramide as organocatalyst. The scope of the reaction provides enantiomerically enriched α-hydroxy phosphonates with yields from 40% to >95% and enantioselectivities from 64% to >99%. Furthermore, the use of this methodology has been demonstrated to form a tetrasubstituted carbon stereocenter, generating an acetophenone derivative in situ, using diphenyl phosphite. Therefore, this approach represents an asymmetric strategy for constructing chiral C−P bonds, which are of interest to the pharmaceutical industry.

Posted in Uncategorized | Leave a comment

A new article just come out!

Posted on March 13, 2023 by mmaamarq

Catalysis-free synthesis of thiazolidine–thiourea ligands for metal coordination (Au and Ag) and preliminary cytotoxic studies, Salvador-Gil, D.; Herrera, R. P.; Gimeno, M. C.  Dalton Trans. 2023. DOI: https://doi.org/10.1039/D3DT00079F.

Abstract. The reaction of propargylamines with isothiocyanates results in the selective formation of iminothiazolidines, aminothiazolines or mixed thiazolidine–thiourea compounds under mild conditions. It has been observed that secondary propargylamines lead to the selective formation of cyclic 2-amino-2-thiazoline derivatives, while primary propargylamines form iminothiazoline species. In addition, these cyclic thiazoline derivatives can further react with an excess of isothiocyanate to give rise to thiazolidine–thiourea compounds. These species can also be achieved by reaction of propargylamines with isothiocynates in a molar ratio of 1 : 2. Coordination studies of these heterocyclic species towards silver and gold with different stoichiometries have been carried out and complexes of the type [ML(PPh3)]OTf, [ML2]OTf (M = Ag, Au) or [Au(C6F5)L] have been synthesised. Preliminary studies of the cytotoxic activity in lung cancer cells have also been performed in both ligands and complexes, showing that although the ligands do not exhibit anticancer activity, their coordination to metals, especially silver, greatly enhances the cytotoxic activity.

Posted in Publication, Raquel P. Herrera, Research | Tagged , , , , , , , , | Leave a comment

Help us spread the Fanny’s 3Min video

Posted on March 8, 2023 by mmaamarq

We are participating in the IV edition of the scientific dissemination contest of CSIC “Yo investigo. Yo soy CSIC” with the Fanny’s video in 3 minutes.

If you like the video, please give us a like in youtube! Thank you!

Posted in Scientific dissemination | Tagged , , , , , | Leave a comment

Jandro, the new PhD student

Posted on February 9, 2023 by mmaamarq

Jandro has been recently arrived to Zaragoza from Galicia full of hope. He expleined to us his interesting previous research during his Bachelor and Master Theses.

He is already an HOCA member 😉 Welcome and good luck!

Posted in PhD thesis, Seminar | Tagged , , | Leave a comment