
Alejandro BaezaUniversity of Alicante | UA · Institute of Organic Synthesis
Alejandro Baeza
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Publications (72)
The hydrocyanation of alkenes can be considered a straightforward methodology that gives access to different functionalized organic chemistry entities. This is due to nitrile's high versatility, which can easily undergo further transformations. However, this process has traditionally employed hazardous hydrogen cyanide as the hydrocyanation agent....
The synthesis of (E)-2-(1,3-diphenylallyl)-3,5-dimethoxyphenol is described by means of the reaction of 3,5-dimethoxyphenol with (E)-1,3-diphenylprop-2-en-1-ol in 1,1,1,3,3,3-hexafluoroispropanol (HFIP), which acts as a solvent and reaction promoter. The reaction proceeds smoothly to afford the mentioned compound in high yield under a metal and add...
The synthesis of methyl 3,3-bis[4-(dimethylamino)phenyl]-2,2-dimethylpropanoate is achieved by means of the alkylation of methyl isobutyrate silyl enol ether with bis[4-(dimethylamino)phenyl]methanol, facilitated by using 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as a solvent and reaction promoter. The reaction proceeds smoothly to produce the menti...
The diastereo- and enantioselective allylation of ketones remains a synthetic challenge, with transition metal catalysis offering the most applied methods. Here, a boron-catalyzed allylation of ketones with allenes is presented. Excellent yield, regioselectivity, and diastereoselectivity were found across functionalized substrates. The reaction was...
High oxidation‐state carbonyl coupling partners including esters and lactones were reacted with enones to give aldol‐type products directly using two‐fold organoborane catalysis. This new retrosynthetic disconnection to aldol‐type products is compatible with enolisable coupling partners, without self‐condensation, and couples the high reactivity of...
High oxidation‐state carbonyl coupling partners including esters and lactones were reacted with enones to give aldol‐type products directly using two‐fold organoborane catalysis. This new retrosynthetic disconnection to aldol‐type products is compatible with enolisable coupling partners, without self‐condensation, and couples the high reactivity of...
The oxidative dehydrogenation of N‐heterocyclic compounds by using H2O2 as oxidant in combination with polar solvents such as 1,1,1,3,3,3‐hexafluoroisopropanol (HFIP) and H2O is described. Among these two solvents, the best yields for the heteroaromatic compounds were generally achieved in HFIP. However, it is remarkable, that the use of a non toxi...
The oxidative cleavage of indoles (Witkop oxidation) involving the use of H2O2 or urea hydrogen peroxide in combination with a polar solvent has been described. Among these solvents, 1,1,1,3,3,3‐hexafluoroisopropanol (HFIP) stands out as the one affording the corresponding 2‐ketoacetanilides generally in higher yields The protocol described has als...
An electrochemical study using the cyclic voltammetry method was carried out on some previously prepared merocyanines salts, namely thiazolideniumsulfonate salts 5a-b, and thiazolidenium chloride salts 6a-b, and merocarbocyanines salts, namely alkylidenthiazolidenium sulfonate salt 5c, and alkylidenthiazolidenium chloride salt 6c. These salts are t...
The straightforward synthesis of N,N-disubstituted formamides using 1,1,1,3,3,3-hexafluoroispropanol (HFIP) and H2O2 combination is described. The unique features of HFIP allowed the utilization of a green oxidant such as H2O2 and the products, arising from an oxidation-rearrangement sequence, were obtained in good to high yields under smooth react...
In the present work, the employment of fluorinated alcohols, specifically 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), as solvent and promoter of the catalyst-free synthesis of substituted tetrahydrofuranes through the addition of electron-rich alkenes to epoxydes is described. The unique properties of this fluorinated alcohol, which is very different...
The straightforward oxidation of electron-rich arenes, namely phenols, naphthols and anisole derivatives under mild reaction conditions is described by means of the use of environmentally benign HFIP-UHP system. The corresponding quinones or hydroxylated arenes, were obtained in moderate to good yields.
Compared with conventional volatile organic solvents (VOCs), deep eutectic solvents (DESs) are typically more synthetically accessible from commodity chemicals using solvent‐/waste‐free, nontoxic, and biodegradable processes. This chapter presents an overview of DESs as designed solvents to create nanomaterials, including isotropic and shape‐contro...
The demand for chiral organic entities for different industrial purposes has grown exponentially in the last decades. [...]
The use of readily available chiral trans-cyclohexanediamine-benzimidazole derivatives as bifunctional organocatalysts in the asymmetric electrophilic amination of unprotected 3-substituted oxindoles is presented. Different organocatalysts were evaluated; the most successful one contained a dimethylamino moiety (5). With this catalyst under optimiz...
The asymmetric synthesis of 3‐substituted oxindoles is a topic of considerable importance because these functionalized heterocycles are found in many natural products and drugs. In the last decade, significant advances have been made towards the asymmetric synthesis of 3‐heteroatom‐substituted oxindoles as a result of major improvements in asymmetr...
The Sonogashira cross-coupling reaction is the most frequently employed synthetic procedure for the preparation of arylated alkynes, which are important conjugated compounds with multiple applications. Despite of their rather high price, this reaction is usually catalyzed by palladium species, making the recovery and reuse of the catalyst an intere...
The synthesis and the evaluation as organocatalysts of new chiral guanidines derived from benzimidazoles in the enantioselective α-amination of 1,3-dicarbonyl compounds using di-t-butylazodicarboxylate as aminating agent is herein disclosed. The catalysts are readily synthesized through the reaction of 2-chlorobezimidazole and a chiral amine in mod...
A metal-free protocol for the reaction of silyl enol ethers with allylic alcohols based on the use of 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) as promoter able to activate both reactants, is herein described. This simple and straightforward transformation proceeds under smooth conditions rendering the corresponding allylated products generally in g...
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, con...
Palladacycles are highly efficient precatalysts in cross-coupling reactions whose immobilization on carbonaceous materials has been hardly studied. Herein, we report a detailed study on the synthesis and characterization of new oxime palladacycle-graphene oxide non-covalent materials along with their catalytic activity in the Suzuki-Miyaura reactio...
The asymmetric allylic alkylation reaction of β ‐keto esters catalyzed by copper complex t BuBOX‐Cu(OTf) 2 employing allylic alcohols as environmentally friendly electrophilic partner, is herein described. This new protocol renders in general the corresponding allylic products with two consecutive all‐carbon stereocenters in good both yields and en...
Graphene oxide (GO) and carboxylic acid-functionalized GO (GO-CO2H) have been found to efficiently promote the heterogeneous and environmentally friendly pinacol rearrangement of 1,2-diols and the direct nucleophilic substitution of allylic alcohols. In general, high yields and regioselectivities are obtained in both reactions using 20 wt% of catal...
The catalytic asymmetric construction of chiral quaternary stereocenters is a continual area of research for organic chemists. In this sense, when a chlorine atom is introduced to a quaternary stereocenter, the synthetic difficulty of the resulting molecule increases along with its significance. This is true not only because of the intrinsic intere...
Bifunctional chiral 2-aminobenzimidazole derivatives 1 and 2 catalyze the enantioselective stereodivergent α-chlorination of β-ketoesters and 1,3-diketone derivatives with up to 50% ee using N-chlorosuccinimide (NCS) or 2,3,4,4,5,6-hexachloro-2,5-cyclohexadien-1-one as electrophilic chlorine sources.
This microreview summarizes the use of deep eutectic solvents (DESs) and related melts in organic synthesis. Solvents of this type combine the great advantages of other proposed environmentally benign alternative solvents, such as low toxicity, high availability, low inflammability, high recyclability, low volatility, and low price, avoiding many d...
In contrast to cyclic 1,3-dicarbonyl compounds, which are aminated in high yields and with low to good enantioselectivities, acyclic derivatives afford racemic mixtures.
Over the past decade, a great effort has been made by the chemical community to improve the efficiency of organic transformations and allow sustainable processes. Merging the use of supported and recyclable organocatalysts and aqueous conditions for the asymmetric synthesis of valuable molecules, has led to outstanding contributions in the area of...
The first organocatalyzed asymmetric alkylation of activated methylene compounds using benzylic and allylic alcohols as alkylating agents through dual hydrogen bond activation in an SN1-type reaction is reported. This green protocol employs a bis(2-aminobenzoimidazole) in combination with an achiral Bronsted acid as a bifunctional catalytic system...
Two series of mesoporous hybrid iron(III) complex–silica aerogels were prepared in one-pot synthesis by using the sol–gel coordination chemistry approach. The use of the ligands 3-(2-aminoethylamino)propyltrimethoxysilane and 2-(diphenylphosphino)ethyltriethoxysilane, both with terminal triethoxysilyl groups, were used to incorporate metal complexe...
The novel green process produces water as the only by-product and is applied to a wide range of keto esters.
Direct nucleophilic substitution reactions of allylic alcohols are environmentally friendly, since they generate only water as a byproduct, allowing access to new allylic compounds. This reaction has, thus, attracted the interest of the chemical community and several strategies have been developed for its successful accomplishment. This review gath...
The bromonium-promoted cyclization of conjugated aminodienes is described. The reaction proceeds smoothly in the presence of N-bromosuccinimide as halonium promoter, and using N-tosyl-protected aminodienes as substrates, to give the corresponding halocyclization products in high yields and with high diastereoselectivities. It can be envisaged that...
The reaction is environmentally friendly and is applied to various N-, C- and O-nucleophiles.
The copper(II) triflate‐ tert ‐butyl‐bisoxazoline [Cu(OTf) 2 ‐ t‐ Bu‐BOX]‐catalyzed asymmetric alkylation of β‐keto esters using free benzylic alcohols such as xanthydrols, as alkylating agents, is herein described for the first time. This green protocol renders in general the corresponding products with good results in terms of both yields and ena...
The allylic substitution reaction, and particularly the direct allylic amination reaction, of free allylic alcohols in water catalyzed by FeCl3⋅6 H2O is described. This novel environmentally‐friendly methodology allows the use of a wide variety of nitrogenated nucleophiles such as sulfonamides, carbamates, benzamides, anilines, benzotriazoles, and...
Both the Lewis acid as well as the Broensted acid are suitable catalysts for allylic amination reactions.
The direct allylic substitution reaction using allylic alcohols in 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) and 2,2,2-trifluoroethanol (TFE) as reaction media is described. The developed procedure is simple, works under mild conditions (rt, 50 and 70 °C), and proves to be very general, since different nitrogenated nucleophiles and carbon nucleophil...
The use of FeCl3·6H2O and TfOH as readily available and easy-to-handle catalysts for the direct allylic amination reaction using a wide variety of nitrogenated nucleophiles onto different free allylic alcohols is described. Comparative studies between these catalysts, as representative Lewis and Brønsted acids are conducted, concluding that both ar...
(cis/trans) [764-41-0] C4H6Cl2 (MW 125.00) InChI = 1S/C4H6Cl2/c5-3-1-2-4-6/h1-2H,3-4H2 InChIKey = FQDIANVAWVHZIR-UHFFFAOYSA-N (cis) [1476-11-5] InChI = 1S/C4H6Cl2/c5-3-1-2-4-6/h1-2H,3-4H2/b2-1- InChIKey = FQDIANVAWVHZIR-UPHRSURJSA-N (trans) [110-57-6] InChI = 1S/C4H6Cl2/c5-3-1-2-4-6/h1-2H,3-4H2/b2-1+ InChIKey = FQDIANVAWVHZIR-OWOJBTEDSA-N (a versat...
In all cases, the pyrrole products bearing the (E)-side chain are formed with high selectivity.
The enantioselective titanium(IV)-catalyzed cyanobenzoylation of aldehydes using 1:1 BINOLAM/Ti(OiPr)4 mixtures as a precatalyst gave O-aroyl cyanohydrins 4 with good enantiomeric excesses. The standard optimization set carried out on the assumption of Curtin–Hammett behavior, led to no amelioration.Extensive experimental and computational studies...
Extensive experimental and computational studies have been carried out on the enantioselective titanium(IV)-catalyzed cyanobenzoylation of aldehydes using 1:n Binolam:Ti(OiPr)4 mixtures as precatalysts, with the purpose of identifying the key mechanistic aspects governing enantioselectivity. HCN and isopropyl benzoate were detected in the reacting...
Intramolecular hydroaminations of conjugated acyclic aminodienes catalyzed by Lewis acids such as silver triflate, cationic gold complexes, BINAP-copper(II) triflate, iron trichloride, indium(III) bromide, iodine and by TfOH, as a representative Bronsted acid, are evaluated. The reaction proceeds in a 1,4-addition manner through a 5-exo-trig cycliz...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
We have evaluated a wide range of iridium complexes derived from chiral oxazoline-based N,P ligands for the asymmetric hydrogenation of imines and identified three efficient catalysts. These catalysts are readily synthesized by straightforward convenient routes and are air and moisture stable. In the reduction of acetophenone N-arylimines and relat...
Chiral indolines substituted at C-2 or C-3 can be prepared in high yield and excellent enantioselectivity by asymmetric hydrogenation of N-protected indoles by using Ir catalysts with chiral N,P ligands. With less reactive substrates, the reaction had to be carried out at elevated temperature, but even at 60-110 °C very high enantiomeric excesses o...
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
The application of cationic iridium catalysts with chiral oxazoline- or pyridine-based N,P ligands for the asymmetric hydrogenation of different unfunctionalized enamines was reported. N-methyl-N-phenyl- and N-methyl-N-benzly-(1-phynylvinly1)amine were hydrogenated using iridium complexes under 50 bar of H2 in CH2Cl2. It was observed that iridium c...
Iridium complexes of chiral oxazoline-based P,N-ligands proved to be efficient catalysts for the enantioselective hydrogenation of 2-aryl- and 2-alkyl-4H-chromenes. The best results were obtained with a ligand derived from threonine (ThrePHOX), which induced ee values of 95% to >99% in the hydrogenation of 2-methyl-, 2-cyclohexyl- and various 2-ary...
A very simple one-step, environmentally friendly procedure for the synthesis of α-aminonitriles from aldehydes and ketones, using trimethylsilyl cyanide in the absence of solvent, is reported. The active catalyst of this three-component (Strecker) reaction was the amine employed in the transformation. In general, aldehydes react more rapidly than k...
Aluminum complexes of the chiral (R)-or (S)-3,3'-bis(diethylaminomethyl)-1,1'-bi-2,2'-naphthol (BINOLAM) ligand behave as efficient catalysts for the enantioselective cyanation-O-functionalization of aldehydes, thereby leading to enantiomerically enriched O-silyl, O-methoxycarbonyl, or O-phosphate derivatives of cyanohydrins. The enantio-enriched c...
Enantiomerically enriched cyanohydrin O-phosphates, prepared by enantioselective cyanophosphorylation of α,β-unsaturated aldehydes, react regioselectively at the γ-position with organocuprates derived from alkyl Grignard reagents and CuCN to afford chiral γ-alkyl-substituted α,β-unsaturated nitriles. The configuration of the new C–C double bond is...
(R)- or (S)-BINOLAM-AlCl, generated in situ, work as bifunctional catalysts in promoting the enantioselective cyanoalkoxycarbonylation of aldehydes. The reaction is wide in scope and the mechanistic evidence gathered suggests the intervention of an indirect process involving enantioselective hydrocyanation by HCN, followed by O-alkoxycarbonylation....
gamma-Functionalized alpha,beta-unsaturated nitriles are prepared diastereoselectively and enantiospecifically from enantioenriched cyanohydrin-O-phosphates and carbonates derived from alpha,beta-unsaturated aldehydes, either by palladium or iridium-catalyzed nucleophilic allylic substitution reactions with different nucleophiles. Appropriate react...
A very simple one-step environmentally friendly procedure for the synthesis of 0-substituted cyanohydrins from aldehydes and ketones, in the absence of solvent, employing minimum amounts of the corresponding cyanides has been optimised. Aldehydes react more rapidly than ketones using triethylamine as catalyst offering in both cases almost quantitat...
The asymmetric cyanobenzoylation of aldehydes has been carried out for the first time, by reaction with benzoyl cyanide in a process catalysed by either (R)- or (S)-3,3′-bis(diethylaminomethyl)-1,1′-binaphthol BINOLAM–Ti(IV) complexes at room temperature and without additives. The reaction can be described as an overall cyano-O-benzoylation of alde...
The enantioselective synthesis of cyanohydrin O-phosphates by using in situ generated bifunctional catalysts (R)- or (S)-3,3'-bis(diethylaminomethyl)-1,1'-binaphthol-aluminium chloride (binolam-AlCl) is reported. The reaction, which can be described as an overall cyano-O-phosphorylation of aldehydes, has a wide scope and applicability. Evidence is...
Aldehydes and ketones are transformed into racemic cyanohydrin O-phosphates by reaction with stoichiometric amounts of diethyl cyanophosphonate and sub-stoichiometric amounts of triethylamine (10 mol. %), at room temperature in the absence of solvent. This green process takes place in excellent yield and with very short reaction time.
For Abstract see ChemInform Abstract in Full Text.
BINOLAM–AlCl's, binaphthoxide aluminium chloride species generated in situ from either (R)- or (S)-3,3′-bis(diethylaminomethyl)-2,2′-dihydroxy-1,1′-binaphthalene (BINOLAM) behave as Lewis acid–Lewis base (LA-LB) catalysts in the enantioselective addition of methyl cyanoformate to aldehydes at room temperature, thereby leading to the asymmetric synt...