Ductile Metal Oxides Impregnated on Magnetite: New Catalysts in Organic Synthesis

Ramón's group has designed a simple, robust and inexpensive methodology for the impregnation of different transition metal oxides on the surface of magnetite and their use in catalysis

Synthesis of 3,5-Disubstituted Isoxazoles and Isoxazolines in Deep Eutectic Solvents

The synthesis of different 3,5-disubstituted isoxazoles and related isoxazolines using choline chloride:urea as deep eutectic solvent (DES) in a one-pot three step reaction has been accomplished successfully. The use of highly nucleophilic functionalized DES did not affect the process where highly electrophilic reagents or intermediates are involved. The presence of DES showed to be essential since the reaction in absence of this media did not proceed. The DES media could be reused up to five times without a detrimental effect on the yield of the reaction. To exemplify the synthetic potential of this methodology, the reaction was scaled up to the gram scale without any noticeable problem. Finally, different isoxazoles were easily transformed into β-aminoenones.This work was supported by the Spanish Ministerio de Economía y Competitividad (MICINN; Grant CTQ2011-24151) and University of Alicante. J.M.P. thanks the MICINN (FPI program) for her fellowship

Catalyzed addition of acid chlorides to alkynes by unmodified nano-powder magnetite: synthesis of chlorovinyl ketones, furans, and related cyclopentenone derivatives

Inexpensive and commercially available nano-powder magnetite is an excellent catalyst for the addition of acid chlorides to internal and terminal alkynes, yielding the corresponding chlorovinyl ketones in good yields. The process has been applied to the synthesis of 5-chloro-4-arylcyclopent-2-enones, 3-aryl-1H-cyclopenta[a]naphthalen-1-ones, and (E)-3-alkylidene-2,3-dihydro-1H-cyclopenta[a]naphthalen-1-ones, just by changing the nature of the starting acid chloride or the alkyne. All tested processes elapse with an acceptable or excellent regio- and stereo-selectivity. Moreover, the use of the iridium impregnated on magnetite catalyst permits the integration of the chloroacylation process with a second dehydrochlorination–annulation process to yield, in one-pot, 1-aryl-2,4-dialkylfurans in good yields, independently of the nature of the starting reagents, and including the heteroaromatic ones.This work was supported by the current Spanish Ministerio de Economía y Competitividad (Consolider Ingenio 2010 CSD2007-00006 and CTQ2011-24151) and the Generalitat Valenciana (G.V.; PROMETEO 2009/03, FEDER). R.C. thanks to G.V. for a fellowship through the PROMETEO program

Environmentally friendly and regioselective C3-alkylation of indoles with alcohols through a hydrogen autotransfer strategy

The direct alkylation of indoles using KOH and alcohols, as initial source of the electrophile, under solvent-free conditions is a safe and environmentally benign strategy for selective modification of these structures at the C3-position, without using hazardous and difficult to handle bromide or iodide derivatives or toxic and expensive transition metal catalysts. The protocol shows a broad scope, including halogenated indoles and secondary alcohols.This work was supported by the current Spanish Ministerio de Economía y Competitividad (Consolider Ingenio 2010 CSD2007-00006, CTQ2011-24151) and the Generalitat Valenciana (G.V.; PROMETEO 2009/03, FEDER). R.C. thanks to G.V. for a fellowship through the PROMETEO program

Cross-dehydrogenative coupling reaction using copper oxide impregnated on magnetite in deep eutectic solvents

The synthesis of different tetrahydroisoquinolines using choline chloride : ethylene glycol as a deep eutectic solvent (DES) and copper(II) oxide impregnated on magnetite as a catalyst has been accomplished successfully. The copper catalyst amount is the lowest loading ever reported. The presence of DES showed to be essential since the reaction in the absence of this medium did not proceed. A direct proportional relationship was found between the conductivity of DES medium and the yield obtained. The DES and the catalyst could be reused up to ten times without any detrimental effect on the yield of the reaction, with the aerobic conditions making the protocol highly sustainable, where the only waste is water.This work was supported by the Spanish Ministerio de Economía y Competitividad (MICINN; CTQ2011-24151) and the University of Alicante. J. M. P. thanks the MICINN (FPI program) for her fellowship

Osmium impregnated on magnetite as a heterogeneous catalyst for the syn-dihydroxylation of alkenes

A new catalyst derived from osmium has been prepared, fully characterized and tested in the dihydroxylation of alkenes. The catalyst was prepared by wet impregnation methodology of OsCl3·3H2O on a commercial micro-magnetite surface. The catalyst allowed the reaction with one of the lowest osmium loadings for a heterogeneous catalyst and was selective for the monodihydroxylation of 1,5-dienes. Moreover, the catalyst was easily removed from the reaction medium by the simple use of a magnet. The selectivity of catalyst is very high with conversions up to 99%. Preliminary kinetics studies showed a first-order reaction rate with respect to the catalyst.This work was supported by the Spanish Ministerio de Economía y Competitividad (CTQ2011-24151). J. M. P. thanks the M.E.C. for a fellowship through the FPI program

Bio-renewable enantioselective aldol reaction in natural deep eutectic solvents

Among the deep eutectic solvents (DES), natural deep eutectic solvents (NADES) formed by D-glucose and racemic malic acid are suitable media to perform the enantioselective L-proline catalyzed intermolecular aldol reaction, creating simultaneously and selectively a C–C bond and a new stereocenter. The scope of the reaction was found to be broad, with products being obtained with good levels of diastereo- and enantioselectivities. Furthermore, when the reaction was performed at a large scale, the catalyst together with the reaction media can be recovered by simple water extraction and reused at least three times affording similar results. Therefore, the use of NADES as reaction media to carry out a VOC-free selective process has been demonstrated for the first time. The process is clean, cheap, simple and scalable and meets most of the criteria to be considered as a sustainable and bio-renewable process, with the reaction media and catalyst arising directly from Nature.This work was supported by the University of Alicante (VIGROB-173 and UAUSTI13-09)

Multicomponent Azide-Alkyne Cycloaddition Catalyzed by Impregnated Bimetallic Nickel and Copper on Magnetite

A new bimetallic catalyst derived from nickel and copper has been used successfully for the first time in the multicomponent reaction of terminal alkynes, sodium azide, and benzyl bromide derivatives. The presence of both metallic species on the surface of magnetite seems to have a positive and synergetic effect. The catalyst loading is the lowest ever published for a catalyst of copper anchored on any type of iron support. The catalyst could be easily removed from the reaction media just by magnetic decantation and it could be reused up to ten times without any negative effect on the initial results

Indium-mediated allylation of carbonyl compounds in deep eutectic solvents

This study describes, for the first time, the in situ generation of indium organometallic reagents in environmentally friendly deep eutectic solvents (DESs). The allylation process of different carbonyl compounds is achieved mediated by indium metal and using cheap allyl chloride derivatives. The unique DES properties allow to perform the reaction at room temperature and under air, obtaining yields ranging from 45% to 99%. It is possible to recycle the reaction medium for at least four consecutive cycles without much decrease of the observed results. Also, a linear correlation between the yield of the reaction and the density of the DESs is observed.This work was supported by the University of Alicante (VIGROB-316FI and VIGORB20-170) and the Spanish Ministerio de Economia, Industria y Competitividad (PGC2018-096616-B-100). NGG and BS thank Generalitat Valenciana (ACIF/2020/186 and ACIF/2017/211, respectively) for their fellowships

Recent Advances in Asymmetric Organocatalyzed Conjugate Additions to Nitroalkenes

The asymmetric conjugate addition of carbon and heteroatom nucleophiles to nitroalkenes is a very interesting tool for the construction of highly functionalized synthetic building blocks. Thanks to the rapid development of asymmetric organocatalysis, significant progress has been made during the last years in achieving efficiently this process, concerning chiral organocatalysts, substrates and reaction conditions. This review surveys the advances in asymmetric organocatalytic conjugate addition reactions to α,β-unsaturated nitroalkenes developed between 2013 and early 2017.We thank the financial support from the Spanish Ministerio de Economía, Industria y Competitividad (CTQ2015-66624-P) and the University of Alicante (UAUSTI16-03, AUSTI16-10, VIGROB-173, VIGROB-285)