Propargylamines paper, just published!

Effort has reward… congrats!! 😉

Unconventional Gold-Catalyzed One-Pot/Multicomponent Synthesis of Propargylamines Starting from Benzyl Alcohols, Zárate-Roldán, S.; Gimeno, M. C.; Herrera, R. P. Catalysts 2021, 11, 513. https://doi.org/10.3390/catal11040513.

Abstract. A formal homogeneous gold-catalyzed A3-coupling, starting from benzyl alcohols, is reported for the straightforward synthesis of propargylamines. This is the first process where these highly valuable compounds have been synthesized, starting from the corresponding alcohols in a one-pot oxidation procedure using MnO2, followed by a HAuCl4·3H2O catalyzed multicomponent reaction. The final products are obtained with very good yields in short reaction times, which is of fundamental interest for the synthesis of pharmaceuticals. The usefulness and efficiency of our methodology is successfully compared against the same reaction starting from aldehydes.

Keywords. benzyl alcohols; gold; multicomponent; one-pot; propargylamine

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Happy birthday Dr. Herrera!!!

Kisses from all current and former HOCA’s members and Gimeno’s group!!

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Stepping strong!!

Our young Sandra Ardevines has received the award “Casañal Poza” for the best academic record of the Degree in Chemistry 2019-20.

Congratulations!!!!

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Chemical reviews just published!

Main Avenues in Gold Coordination Chemistry, Herrera, R. P.; Gimeno, M. C. Chem. Rev. 2021, https://doi.org/10.1021/acs.chemrev.0c00930.

Hard, but gratifying work! Congratulations!!

Abstract. In this contribution, we provide an overview of the main avenues that have emerged in gold coordination chemistry during the last years. The unique properties of gold have motivated research in gold chemistry, and especially regarding the properties and applications of gold compounds in catalysis, medicine, and materials chemistry. The advances in the synthesis and knowledge of gold coordination compounds have been possible with the design of novel ligands becoming relevant motifs that have allowed the preparation of elusive complexes in this area of research. Strong donor ligands with easily modulable electronic and steric properties, such as stable singlet carbenes or cyclometalated ligands, have been decisive in the stabilization of gold(0) species, gold fluoride complexes, gold hydrides, unprecedented π complexes, or cluster derivatives. These new ligands have been important not only from the fundamental structure and bonding studies but also for the synthesis of sophisticated catalysts to improve activity and selectivity of organic transformations. Moreover, they have enabled the facile oxidative addition from gold(I) to gold(III) and the design of a plethora of complexes with specific properties.

Key words. Anions, Reaction products, Metals, Gold, Ligands

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Fer already “Doc”

Today, February 1st, Fernando defended his PhD thesis with great honors.

You got it! Congratulations, Fer!

THANKSSSS and good luck!

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Happy birthday Juanvi!!

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Happy birthday Guillermo!

Last December 28th, Guillermo blew out twenty-odd candles 😉

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Happy birthday Eduardo!

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Happy birthday Conchita and Alberto!

Thousands kisses from HOCAs!

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HOCA (aza-Henry reaction) in The 24th International Electronic Conference on Synthetic Organic Chemistry (Nov 2020)

Asymmetric aza-Henry reaction of hydrazones

I. G. Sonsona, J. V. Alegre-Requena,* E. Marqués-López, M. C. Gimeno, R. P. Herrera*

10.3390/ecsoc-24-08411 (registering DOI)

Abstract: In this work, the enantioselective organocatalyzed addition of nitroalkanes to N-benzoyl hydrazones has been developed for the first time. In order to find a chiral organocatalyst suitable to promote the reaction under high stereo-control and reaction rates, the catalytic activity of several cinchone-derived Brønsted bases was evaluated. As a result of the study, simple quinine alkaloid was able to catalyze, in the optimal reaction conditions, the synthesis of alkyl substituted betha-nitroalkylhydrazides with good yields (up to 91%) and enantiomeric excesses (up to 77%), while quinidine alkaloid was used to obtain the opposite enantiomer with similar catalytic results. Moreover, the further recrystallization of the corresponding enantio-enriched mixtures led to the obtainment of each enantiomer with ee up to 94%. The scope of the catalytic method was explored (14 examples), and the effect of substitutients present in the substrates was evaluated in terms of activity and selectivity. Additionally, the catalyzed reaction pathway was study ab initio in order to understand the successful chiral induction by the catalyst. Hence, in the transition state of the rate limiting step (RLS), quinine is acting as bifunctional catalyst activating both substrates simultaneously. This step involves the protonation of the hydrazone and the attack of the nitronate anion to the sp2 prochiral center in a concerted process. Experimental kinetic studies support this reaction mechanism.

Keywords: Organocatalysis; Asymmetric catalysis; aza-Henry reaction

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