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In the early 2000s, the Sigma Receptor (SR) family was identified as potential “druggable” target in cancer treatment. Indeed, high density of SRs was found in breast, lung, and prostate cancer cells, supporting the idea that SRs could play a role in tumor growth and progression. Moreover, a link between the degree of SR expression and tumor aggressiveness has been postulated, justified by the presence of SRs in high metastatic-potential cancer cells. As a consequence, considerable efforts have been devoted to the development of small molecules endowed with good affinity towards the two SR subtypes (S1R and S2R) with potential anticancer activity. Herein, we report the synthesis and biological profile of aryl-alkyl(alkenyl)-4-benzylpiperidine derivatives - as novel potential anticancer drugs targeting SR. Among them, 3 (RC-106) exhibited a preclinical profile of antitumor efficacy on a panel of cell lines representative of different cancer types (i.e. Paca3, MDA-MB 231) expressing both SRs, and emerged as a hit compound of a new class of SR modulators potentially useful for the treatment of cancer disease.

The new motif – α,α-difluoromethyl thioamide – has been assembled starting from isothiocyanate (as thioamide precursor) and a formal difluoromethyl-carbanion generated from commercially available TMSCHF2. Upon proper activation of this reagent with potassium tert-amylate, the high-yielding transfer of the difluorinated nucleophile takes place under high chemocontrol. Various sensitive functionalities (e.g. ester, nitrile, nitro, azido groups) can be accommodated across the isothiocyanate core, thus allowing a wide scope. The methodology is highly flexible and adaptable to prepare analogous α,α-difluoromethyl oxoamides by conveniently using isocyanates as the electrophilic building-blocks.

The homologation of Weinreb amides into difluoromethylketones with a formal nucleophilic CHF

The homologation of Weinreb amides into difluoromethylketones with a formal nucleophilic CHF2 transfer agent is reported. Activating TMSCHF2 with potassium tert-amylate enables a convenient access ...

Neurodegenerative disorders represent one of the main therapeutic challenges of our time. [...]

An efficient Pd(II)-catalyzed cascade approach was established for the synthesis of 9-chloro-1

An expeditious, high-yielding synthesis of rare α-fluoroepoxides and α-fluoroaziridines through the addition of the unkown fluoroiodomethyllithium (LiCHIF)—formed via deprotonation the commercially available fluoroiodomethane with a lithium amide base—to carbonyl-like compounds is documented. The ring-closure reactions, leading to α-fluorinated three-membered heterocycles, rely on the diversely reactive C–I and C–F bonds. Excellent chemoselectivity was observed in the presence of highly sensitive functionalities—aldehyde, ketone, nitrile, alkene—which remained untouched during the homologation sequence.

The structure and spectroscopic properties of the amide bond are a topic of fundamental interest in chemistry and biology. Herein, we report 17O NMR and 15N NMR spectroscopic data for four series of sterically-hindered acyclic amides. Despite the utility of 17O NMR and 15N NMR spectroscopy, these methods are severely underutilized in the experimental determination of electronic properties of the amide bond. The data demonstrate that a combined use of 17O NMR and 15N NMR serves as a powerful tool in assessing electronic effects of the amide bond substitution as a measure of electrophilicity of the amide bond. Notably, we demonstrate that steric destabilization of the amide bond results in electronically-activated amides that are comparable in terms of electrophilicity to acyl fluorides and carboxylic acid anhydrides.

Subunit-selective modulation of γ-aminobutyric acid type A receptors (GABAAR) is considered to exert fewer side effects compared to unselective clinically used drugs. Here, the β2/3 subunit-selective GABAAR modulators valerenic acid (VA) and loreclezole (LOR) guided the synthesis of novel subunit-selective ligands with simplified structures. We studied their effects on GABAARs expressed in Xenopus laevis oocytes using two-microelectrode voltage clamp technique. Five compounds showed significantly more efficacious modulation of GABA-evoked currents than VA and LOR with retained potency and selectivity. Compound 18 [(E)-2–Cyano-3-(2,4-dichlorophenyl)but-2-enamide] induced the highest maximal modulation of GABA-induced chloride currents (Emax: 3114 ± 242%), while 12 [(Z)-3-(2,4-dichlorophenyl)but-2-enenitrile] displayed the highest potency (EC50: 13 ± 2 μM). Furthermore, in hippocampal neurons 12 facilitated phasic and tonic GABAergic inhibition, and in vivo studies revealed significantly more potent protect...

A conceptually novel, high‐yielding, mono‐ or bis‐homologation was realized with lithium halocarbenoids and enables the one‐step, fully chemocontrolled assembly of a new class of quaternary trifluoromethyl aziridines. Trifluoroacetimidoyl chlorides (TFAICs) act as convenient electrophilic platforms, enabling the addition of either one or two homologating elements by simply controlling the stoichiometry of the process. Mechanistic studies highlighted that the homologation event, carried out with two different carbenoids (LiCH2Cl and LiCH2F), leads to fluoromethyl analogues in which the first nucleophile is employed for constructing the cycle and the second for decorating the resulting molecular architecture.

The acylation of α-substituted carbanion-type reagents (MCR1R2X; X = halogen, OR, SR, NR3R4, SeR, etc.) with Weinreb amides constitutes a highly versatile and flexible approach for accessing α-functionalized ketones. In this short review we will present a series of transformations—from our own and the work of others—documenting the general applicability of the methodology. Chemoselectivity is uniformly manifested including for critical substrates featuring additional electrophilic functionalities or sterically demanding elements. Importantly, the stereochemical information contained in the Weinreb amides can be fully transferred to the targeted ketones without affecting the optical purity. The protocol is also applicable to chiral carbanions generated through sparteine-mediated asymmetric deprotonation: the careful design of the experimental procedure allows recycling of the sparteine and the Weinreb ‘amine’ (N,O-dimethylhydroxylamine), thus improving the sustainability perspective of the processes.1 Introduction1.1 The Problem of the Synthesis of α-Substituted Ketones1.2 Weinreb Amides: General Features and Preparation2 Synthesis of α-Substituted Ketones2.1 α-Haloketones2.2 Synthesis of α-Cyanoketones2.3 Synthesis of α-Oxyketones2.4 Synthesis of β-Oxo Thioethers (α-Thioketones)2.5 Synthesis of Chiral α-Oxy and α-Nitrogen Ketones via the Sparteine-Mediated Generation of Optically Active Organolithiums2.6 Synthesis of α-Selenomethyl Ketones2.7 Reactivity of α-Phosphorus Carbanions with Weinreb Amides2.8 Modification of the Weinreb Amide Core: The CLAmP Reagent3 Competing Attack of Nucleophiles at More Reactive Electrophilic Sites than Weinreb Amides4 Conclusions

Abstract The Tiffeneau–Demjanov rearrangement can be regarded as an interesting alternative to the more common semi-pinacol transposition. It is usually employed for ring extension but, under specific conditions, it can also be used for ring contraction. Compared to other techniques, such as the Demjanov rearrangement or homologations with diazo compounds, the Tiffeneau–Demjanov pathway presents attractive features including high yielding and selective processes. Ring enlargements follow very strict and simple rules, such as the movement of the less substituted carbon and retention of the configuration. The rearrangement process is mainly affected by steric factors, due to presence of neighbouring groups, rather than electronic ones. The ring contraction may be achieved positioning the amine within the ring, thus achieving a high level of control. Unfortunately, applications of the reaction in modern homologation chemistry are rare; therefore, the aim of the review is re-proposing to the synthetic community the versatility of this venerable reaction and thus, spurring its employment for tackling challenging homologations processes. Graphic abstract

The well‐established Hoppe–Beak chemistry, which involves enantioselective generation of organolithium compounds in the presence of (−)‐sparteine, was revisited and applied to unprecedented acylations with Weinreb amides to access highly enantioenriched α‐oxyketones and cyclic α‐aminoketones. Recycling of the sustainable solvent cyclopentyl methyl ether, sparteine, and the released Weinreb “amine” [HNMe(OMe)] was possible through a simple work‐up procedure that enabled full recovery of these precious materials. The methodology features a robust scope and flexibility, thus allowing the enantioselective preparation of scaffolds amenable of further derivatization.

Formylation reactions are fundamental operations in synthetic chemistry allowing the incorporation into a given structure formyl groups amenable to further deiivatization. Conceptually, the introduction of such groups through the reaction between an electrophilic donor and a nucleophilic acceptor (i.e. organometallic reagent) constitutes a reliable technique with widespread applications. In this Highlight, we summarize the effectiveness of the so called Comnins-Meyers amide - [2-(N-methyl-N-formylamino]pyridine - in such a chemistry with vistas to the synthesis of natural products and biologically active substrates.

α-Fluoromethyl selenoethers were prepared through a sequential one-pot diselenide reduction-fluoromethylation with the fluorinated, highly manipulable C1 source ICH2F. The reaction benefited from the employment of the environmentally friendly solvent MeTHF (2-methyltetrahydrofuran) which enabled to maximize the efficiency of both steps of the technique. A series of variously functionalized analogues – featuring a remarkable degree of stability imparted by selenium - could be chemoselectively accessed in high yield and purity through an intuitive and experimentally simple protocol.

The transfer of a α-methyl phenylseleno carbanion to variously functionalized N-aryl and N-sulfonyl imines is reported. The fast selenium-lithium exchange conducted on a diselenoacetal with n-BuLi enables the generation of the attacking homologative nucleophile under chemoselective conditions preserving concomitant potentially sensitive functionalities to the lithiating conditions. Uniformly high yields were observed, thus establishing a valuable and conceptually simple approach to the title compounds.

alpha-Halomethyllithium carbenoids are useful homologating reagents which - reacting under proper reaction conditions as carbanions - enable the installation via nucleophilic addition of a reactive halomethyl fragment onto a preformed carbon-heteroatom bond. The pronounced thermolability represented - since seminal studies by Kobrich - the Achilles' heel of these reagents: the use of Barbier-type methodologies (i.e., the electrophile should be present in the reaction mixture prior to the formation of the carbenoid) was pivotal in order to suppress decomposition through -elimination processes. Nowadays, the use of low temperatures (-78 degrees C) guarantees reliable procedures and, significantly, the employment of microreactor technologies allows external trapping to be performed even at higher temperatures as reported by Luisi. We will discuss the -halomethyllithium-mediated homologations of a series of carbon electrophiles such as carbonyl compounds, imines, esters, Weinreb amides, and isocyanates.

An efficient, chemoselective approach to spiro-epoxyoxindoles via the addition of chloromethyllithium followed by ring-closure of the intermediate alkoxide is reported. Chemoselectivity is fully preserved in the presence of different electrophilic sites. The synthetic potential of selected spiro-epoxyindoles has been exploited in the copper(I)-catalyzed intramolecular oxyarylation of an alkyne and in the formation of N,N-dimethylisoindigo via the addition of dihalocarbenoids.

The addition of carbon (Grignard and organolithium reagents) and hydride nucleophiles (Schwartz reagent) to isocyanates and isothiocyanates constitutes a versatile, direct and high yielding approach to the synthesis of functionalized (thio)amide derivatives including haloamides and formamides. The chemoselective delivery of a nucleophilic (eventually configurationally stable) organometallic species to a given iso(thio)cyanate is the crucial parameter for the success of the strategy. Thus, the influence of the factors governing classical methodologies (e.g. dehydrative condensation) such as steric hindrance and electronic properties of the reactants become practically negligible.

The nucleophilic addition of widely available and variously functionalized organolithium reagents to isothiocyanates represents a straightforward, high-yielding, one-pot method to access secondary thioamides. The simple reaction conditions required and the broad scope (>50 cases examples) makes it a robust and reliable method to access both simple and complex thioamides, including enantiopure ones. Noxious and unpleasant-smelling sulfurating agents, usually employed in the literature established methods, are avoided during the whole synthetic procedure thus, rendering the protocol highly attractive, also for sustainability aspects.

Subunit-selective modulation of γ-aminobutyric acid type A receptors (GABA

A direct, single synthetic homologative transformation of halostannanes into mono- or di-substituted methyl analogues is documented. Critical for the success of the operation is the excellent nucleophilicity of carbenoid-like methyllithium reagents (LiCHXY, X, Y = halogen, OR, and CN): by simply individuating the reagents’ substitution pattern, the desired functionalized fragment is delivered to the electrophile. The wide scope of the protocol is evidenced also in the case of analogous halogermanium compounds. The tandem homologation–quenching with nucleophiles and the use of α-chloroallyllithium is also discussed.

The transfer of a reactive nucleophilic CH2X unit into a preformed bond enables the introduction of a fragment featuring the exact and desired degree of functionalization through a single synthetic operation. The instability of metallated α-organometallic species often poses serious questions regarding the practicability of using this conceptually intuitive and simple approach for forming C–C or C–heteroatom bonds. A deep understanding of processes regulating the formation of these nucleophiles is a precious source of inspiration not only for successfully applying theoretically feasible transformations (i.e. determining how to employ a given reagent), but also for designing new reactions which ultimately lead to the introduction of molecular complexity via short experimental sequences.

Diselenoacetals, previously considered byproducts in homologation tactics en route to α-selenoketones, are herein found to be excellent starting materials for this purpose. The easy selenium/lithium exchange they undergo affords seleno carbanions which are smoothly added to Weinreb amides to chemoselectively prepare α-aryl- and α-alkyl seleno methylketones through a single chemical operation. No racemization events are observed in the presence of optically pure starting materials.

Spiro-epoxyoxindoles containing an unsubstituted methylene fragment in the oxirane ring are excellent building blocks in organic synthesis due to the high reactivity conferred by the three-membered oxygenated cycle. In this minireview, a concise survey of the methods of their synthesis and examples of reactivity with carbon and nitrogen nucleophiles is presented, with a particular focus on the stereochemical aspects. The review covers the literature for the last twenty years.

Primary and secondary α-halomethyl diazoketones generated via Arndt–Eistert chemistry with minimum loading of diazomethane efficiently alkylate aromatic amines in the presence of calcium oxide to furnish the corresponding α-arylamino diazoketones under full chemocontrol. Such a simple inorganic acid scavenger fully neutralizes the hydrohalic acid formed during the nucleophilic displacement which otherwise would immediately react to produce the corresponding α-haloketone. The methodology can be further exploited in analogous acylation-type processes on secondary arylamino diazoketones. In depth spectroscopic (1H, 13C, and 15N NMR ) and crystallographic analyses document interesting structural features of these previously unknown diazo derivatives.

Lithium halocarbenoids are versatile reagents for accomplishing homologation processes. The fast α-elimination they suffer has been considered an important limitation for their extensive use. Herein, we present a series of practical considerations for an effective employment in the homologation of selected carbon electrophiles. Graphical abstract Electronic supplementary material The online version of this article (10.1007/s00706-018-2232-9) contains supplementary material, which is available to authorized users.

In this manuscript we report on the design, synthesis and evaluation of dual Sigma 1 Receptor (S1R) modulators/Acetylcholinesterase (AChE) inhibitors endowed with antioxidant and neurotrophic properties, potentially able to counteract neurodegeneration. The compounds based on arylalkylaminoketone scaffold integrate the pharmacophoric elements of RRC-33, a S1R modulator developed by us, donepezil, a well-known AChE inhibitor, and curcumin, a natural antioxidant compound with neuroprotective properties. A small library of compounds was synthesized and preliminary in vitro screening performed. Some compounds showed good S1R binding affinity, selectivity towards S2R and N-Methyl- d -Aspartate (NMDA) receptor, AChE relevant inhibiting activity and are potentially able to bypass the BBB, as predicted by the in silico study. For the hits 10 and 20, the antioxidant profile was assessed in SH-SY5Y human neuroblastoma cell lines by evaluating their protective effect against H2O2 cytotoxicity and reactive oxygen species (ROS) production. Tested compounds resulted effective in decreasing ROS production, thus ameliorating the cellular survival. Moreover, compounds 10 and 20 showed to be effective in promoting the neurite elongation of Dorsal Root Ganglia (DRG), thus demonstrating a promising neurotrophic activity. Of note, the tested compounds did not show any cytotoxic effect at the concentration assayed. Relying on these encouraging results, both compounds will undergo a structure optimization program for the development of therapeutic candidates for neurodegenerative diseases treatment.

β,γ-Unsaturated aldehydes with all-carbon quaternary or tertiary α-centers were rapidly assembled from ketones through a unique synthetic operation consisting of 1) C1 homologation, 2) Lewis acid mediated epoxide–aldehyde isomerization, and 3) electrophilic trapping. The synthetic equivalence of a vinyl oxirane and a β,γ-unsaturated aldehyde is the key concept of this previously undisclosed tactic. Mechanistic studies and labeling experiments suggest that an aldehyde enolate is a crucial intermediate. The homologating carbenoid formation plays a critical role in determining the chemoselectivity.

α-Functionalized organolithium reagents (e.g., LiCH2X) are versatile reagents for accomplishing homologations of carbon- and heteroatom-type electrophiles. The proper selection of the reaction conditions allows one to direct their intrinsic ambiphilicity towards the nucleophilic character. Herein, the homologation of various electrophiles ranging from Weinreb amides to isocyanates, carbonyl derivatives, and chalcogenides – with a particular focus on the chemoselectivity of the processes – is summarized. 1 Introduction 2 Homologation of Weinreb Amides 3 Homologation of Cyclic Ketones 4 Homologation of Isocyanates 5 Homologation of Disulfides and Diselenides 6 Conclusions

The tetrahedral intermediates generated upon the addition of halolithium carbenoids (LiCH2X and LiCHXY) to Weinreb amides have been intercepted and fully characterized as O-TMS heminals. The commercially available N-trimethylsilyl imidazole is the ideal trapping agent whose employment, combined with a straightforward neutral Alox chromatographic purification, enables the isolation of such labile species. The procedure could be advantageously extended also for obtaining O-TMS heminals from N-acylpyrroles. These intermediates manifest interesting reactivity including as precursors of more complex carbenoids.

Since the introduction of 2-methyltetrahydrofuran as an useful alternative to the classical tetrahydrofuran, there has been a continuous interest in the synthetic community operating at academic and industrial towards it. In particular, the much higher stability that basic organometallic reagents display in 2-methyltetrahydrofuran makes it suitable for processes involving such sensitive species including asymmetric transformations. The easy formation of an azeotropic mixture with water, the substantial immiscibility with water, and the fact it derives from natural sources (corncobs or bagasse), allow to consider it in agreement with the Anastas’ Geen Chemistry principles. In this minireview, selected examples of its employment in organometallic transformations ranging from carbanions to radical and transition metal-catalyzed processes are provided. Graphical abstract

Chloromethyllithium carbenoid has been chemoselectively added to cyclic enones (5-, 6- and 7-membered systems, including two natural products) to provide chloromethyl allylic alcohols. Under the optimized reaction conditions neither concomitant (n+1) homologation nor conjugate addition or Simmons–Smith-like cyclopropanation takes place. The presence of LiBr is estimated to play a dual role, namely as a carbenoid stabilizer and mild Lewis acid activator of the CO group. Notably, the mesomeric effect caused by β-heteroatom-containing substituents promotes the attack of the reagent at the most activated position.

A novel palladium-catalyzed hydration–olefin insertion cascade assisted by internal nucleophiles was developed for the synthesis of biologically significant 2,3-dihydro-1H-inden-1-ones under mild conditions. A detailed mechanistic study revealed that the assistance of the internal nucleophiles is crucial to trigger the cascade reaction via nucleopalladation of the alkyne moiety. The overall reaction is equivalent to regioselective hydration of alkynes followed by intramolecular Michael addition. This highly efficient and 100% atom-economical domino sequence afforded cis-2,3-disubstituted 2,3-dihydro-1H-inden-1-ones in excellent yields (up to 99%) with complete diastereoselectivity.

The preparation of three-dimensional frameworks with multiple stereocentres from simple acyclic hydrocarbons represents a challenging transformation. Now, starting from simple and readily available reagents, formation of these complex targets can be achieved in just three catalytic transformations with high levels of stereocontrol.

Vinyl bromides bearing an arylamino group in the vicinal position are chemoselectively transformed into interesting α-arylamino-α′-bromoacetones through a straightforward oxidative hydrolysis promoted by calcium hypobromite under mild acidic conditions. Significantly, this particular combination [vinyl bromides and Ca(BrO)2] avoids bromination at both the aromatic ring and activated positions in groups substituting the amine nitrogen. The usefulness of this class of brominated ketones has been shown in a Wittig homologation.

α-Amino-α´-halomethylketones are interesting scaffolds bearing (at least) two sequential electrophilic carbons that by interacting with the nucleophilic moieties of several enzymes, represent the ideal candidates for in vivo and in vitro inhibition studies. In this work a summary of their use as optimal inhibitors of physiologically relevant serine and cysteine proteases is given with a particular emphasis on recently established SAR studies. A brief survey of the most relevant synthetic processes for their obtainment and the importance they possess in synthetic medicinal chemistry is reported.

An efficient and selective procedure for the synthesis of epiminodibenzo[b,f][1,5]diazocines involving a AB

Addition of the in situ generated Schwartz reagent to widely available isocyanates constitutes a chemoselective, high-yielding, and versatile approach to the synthesis of variously functionalized formamides. Steric and electronic factors or the presence of sensitive functionalities (esters, nitro groups, nitriles, alkenes) do not compromise the potential of the method. Full preservation of the stereochemical information contained in the starting materials is observed. The use of formamides in the nucleophilic addition of organometallic reagents (Chida–Sato allylation, Charette–Huang addition to imidoyl triflate activated amides, Matteson homologation of boronic esters) is briefly investigated.

The addition of carbon (Grignard and organolithium reagents) and hydride nucleophiles (Schwartz reagent) to isocyanates and isothiocyanates constitutes a versatile, direct and high yielding approach to the synthesis of functionalized (thio)amide derivatives including haloamides and formamides. The chemoselective delivery of a nucleophilic (eventually configurationally stable) organometallic species to a given iso(thio)cyanate is the crucial parameter for the success of the strategy. Thus, the influence of the factors governing classical methodologies (e.g. dehydrative condensation) such as steric hindrance and electronic properties of the reactants become practically negligible.

An efficient, chemoselective homologation of Weinreb amides to the corresponding variously substituted α-oxyketones has been developed via the addition of lithiated α-oxygenated species. This one-step, experimentally easy, high yielding protocol is amenable not only for accessing simple α-oxyketones but also for more complex substituted ones ranging from primary and secondary alkyl-type to aromatic ones. Full delivery of the stereochemical information contained in the starting materials is observed through both the employment of enantioenriched Weinreb amides and optically active organolithium species.

A high-yielding, one-pot, three-component synthesis of functionalized 2-amino-4H-pyrans from β-dicarbonyl compounds, activated cyanomethylene compounds, and aldehydes, mediated by potassium-exchanged zirconium hydrogen phosphate [α-Zr(KPO4)2], is reported. The protocol shows excellent versatility, as it can be applied to aromatic, aliphatic, or α,β-unsaturated aldehydes under solvent-free conditions.

alpha-Halomethyllithium carbenoids are useful homologating reagents which - reacting under proper reaction conditions as carbanions - enable the installation via nucleophilic addition of a reactive halomethyl fragment onto a preformed carbon-heteroatom bond. The pronounced thermolability represented - since seminal studies by Kobrich - the Achilles' heel of these reagents: the use of Barbier-type methodologies (i.e., the electrophile should be present in the reaction mixture prior to the formation of the carbenoid) was pivotal in order to suppress decomposition through -elimination processes. Nowadays, the use of low temperatures (-78 degrees C) guarantees reliable procedures and, significantly, the employment of microreactor technologies allows external trapping to be performed even at higher temperatures as reported by Luisi. We will discuss the -halomethyllithium-mediated homologations of a series of carbon electrophiles such as carbonyl compounds, imines, esters, Weinreb amides, and isocyanates.

Herein, we show that acyclic amides that have recently enabled a series of elusive transition-metal-catalyzed N-C activation/cross-coupling reactions are highly twisted around the N-C(O) axis by a new destabilization mechanism of the amide bond. A unique effect of the N-glutarimide substituent, leading to uniformly high twist (ca. 90°) irrespective of the steric effect at the carbon side of the amide bond has been found. This represents the first example of a twisted amide that does not bear significant steric hindrance at the α-carbon atom. The (15) N NMR data show linear correlations between electron density at nitrogen and amide bond twist. This study strongly supports the concept of amide bond ground-state twist as a blueprint for activation of amides toward N-C bond cleavage. The new mechanism offers considerable opportunities for organic synthesis and biological processes involving non-planar amide bonds.

The identification of novel pan-sigma receptor (SR) modulators, potentially useful in cancer treatment, represents a new goal of our research. Here, we report on the preparation of novel chiral compounds characterized by a 3-C alkyl chain bridging an aromatic portion to a 4-benzyl-piperidine moiety. All of the studied compounds have been prepared both in racemic and enantiomerically-pure form, with the final aim to address the role of chirality in the SR interaction. To isolate and characterize enantiomeric compounds, high-performance liquid chromatography (HPLC) procedures were set up. A systematic analytical screening, involving several combinations of chiral stationary and mobile phases, allowed us to optimize the analytical resolution and to set up the (semi-)preparative chromatographic conditions. Applying the optimized procedure, the enantiomeric resolution of the studied compounds was successfully achieved, obtaining all of the compounds with an enantiomeric excess higher than 95%. Lastly, the absolute configuration has been empirically assigned to enantiopure compounds, combining the electronic circular dichroism (ECD) technique to the elution order study.