Diffusion-Ordered NMR Spectroscopy (DOSY) of THF Solvated n-Butyllithium Aggregates

Rapid Access to Isoprenoid Quinones through X@RONa-Catalyzed Redox Chain Reaction

Dodecameric sodium alkoxide clusters encaging a halide anion (X@RONa) were shown to be C-C bond formation catalysts in the redox chain reaction of quinones. With up to 30 mol % tert-decanol as the catalyst and stoichiometric base NaH, a great number of chemically sensitive isoprenoid quinones, including health-relevant Coenzyme Q and Vitamin K family compounds, were easily made in one step from their parent quinones and polyprenyl halide. The X@RONa clusters and possible cluster-derived intermediates were studied by characterization techniques, control experiments, and theory. The X@RONa clusters likely facilitated the C-alkylation step by preventing O-alkylation, promoting dissociation of halide from the alkyl chain, and transporting hydride into the nonpolar solvent.

Scalable Transition-Metal-Free Synthesis of Aryl Amines from Aryl Chlorides through X@RONa-Catalyzed Benzyne Formation

Aryl amines are highly useful organic chemicals, but large-scale, transition-metal-free syntheses of aryl amines are surprisingly underdeveloped. A mild and scalable (up to 500 mmol) aryl amine synthesis from benzyne chemistry was invented using easily accessible aryl chlorides as precursors, NaH as a stoichiometric base, and a new type of sodium alkoxide cluster, X@RONa, as a catalyst. The cluster catalyst X@RONa featured an externally hydrophobic dodecameric sodium alkoxide shell housing an encapsulated center anion. The cluster made from methoxy-tert-butanol was found to be the most effective. The intramolecular version of this reaction allowed the synthesis of indolines and indoles. Experimental and computational mechanistic studies revealed that the rate-determining step was likely the transport of solid NaH into the X@RONa cluster in the organic phase.

N-Oxides amplify catalyst reactivity and isoselectivity in the ring-opening polymerization of rac-β-butyrolactone

N-Oxides can amplify the performance of a lanthanum aminobisphenolate catalyst in the ring-opening polymerization (ROP) of rac-β-butyrolactone (rac-BBL) to unprecedented levels (TOF/P_m; At RT: 1900 h^-1/0.73, At -30 °C: 200 h^-1/0.82). Experiments and computations establish donor electronics control catalyst activity, while donor sterics control catalyst deactivation.

Azolium/Hydroquinone Organo-Radical Co-Catalysis: Aerobic C-C-Bond Cleavage in Ketones

Organo-radical catalysts have recently attracted great interest, and the development of this field can be expected to broaden the applications of organocatalysis. Herein, the first example of a radical-generating system is reported that does not require any photoirradiation, radical initiators, or preactivated substrates. The oxidative C-C-bond cleavage of 2-substituted cyclohexanones was achieved using an azolium salt and a hydroquinone as co-catalysts. A catalytic mechanism was proposed based on the results of diffusion-ordered spectroscopy and cyclic voltammetry measurements, as well as computational studies.

Solvation Effects on the Structure and Stability of Alkali Metal Carbenoids

s-Block metal carbenoids are carbene synthons and applied in a myriad of organic transformations. They exhibit a strong structure-activity relationship, but this is only poorly understood due to the challenging high reactivity and sensitivity of these reagents. Here, we report on systematic VT and DOSY NMR studies, XRD analyses as well as DFT calculations on a sulfoximinoyl-substituted model system to explain the pronounced solvent dependency of the carbenoid stability. While the sodium and potassium chloride carbenoids showed high stabilities independent of the solvent, the lithium carbenoid was stable at room temperature in THF but decomposed at -10 °C in toluene. These divergent stabilities could be explained by the different structures formed in solution. In contrast to simple organolithium reagents, the monomeric THF-solvate was found to be more stable than the dimer in toluene, since the latter more readily forms direct Li/Cl interactions which facilitate decomposition via α-elimination.

Structural and electronic studies of substituted m-terphenyl lithium complexes

Spectroscopic and computational investigation of the effects of para-substituted m-terphenyl lithium complexes reveals significant electronic differences at the metal centre.

Yttrium and lanthanum bis(phosphine-oxide)methanides: structurally diverse, dynamic, and reactive

Homoleptic yttrium and lanthanum complexes of bis(phosphineoxide) methanides, RE(HPhL)3 and RE2(HMeL)6, promote the first rare-earth mediated Horner-Wittig and acid-base chemistry consistent with multifunctional reactivity (Lewis-acid/Brønstedbase).

Low-Symmetry β-Diketimine Aryloxide Rare-Earth Complexes: Flexible, Reactive, and Selective

We report the synthesis, characterization, and reactivity of a new low-symmetry β-diketimine featuring a pendant amino(methyl)phenol donor and its corresponding heteroleptic rare-earth (RE) complexes. This includes the first structurally characterized examples of alcoholysis and insertion from an isolated RE^III amide in a β-diketimine framework. The flexible methylene linkage leads to RE^III complexes with tunable dynamic solution behavior that defines their stoichiometric and catalytic reactivity. The addition of a strong neutral donor ligand, tricyclohexylphosphine oxide, suppresses a prevalent catalyst degradation pathway (base-promoted elimination) and dramatically enhances the catalyst performance in the stereospecific ring-opening polymerization of rac-β-butyrolactone. Our results further demonstrate the importance of ligand reorganization in the stoichiometric and catalytic activity of RE^III ions.

The interpretation of small molecule diffusion coefficients: Quantitative use of diffusion-ordered NMR spectroscopy

Measuring accurate molecular self-diffusion coefficients, D, by nuclear magnetic resonance (NMR) techniques has become routine as hardware, software and experimental methodologies have all improved. However, the quantitative interpretation of such data remains difficult, particularly for small molecules. This review article first provides a description of, and explanation for, the failure of the Stokes-Einstein equation to accurately predict small molecule diffusion coefficients, before moving on to three broadly complementary methods for their quantitative interpretation. Two are based on power laws, but differ in the nature of the reference molecules used. The third addresses the uncertainties in the Stokes-Einstein equation directly. For all three methods, a wide range of examples are used to show the range of chemistry to which diffusion NMR can be applied, and how best to implement the different methods to obtain quantitative information from the chemical systems studied.

NMR spectrocopy of organolithium compounds, part XXXIV: Cyclopropyllithium and lithium bromide (1:1) in diethylether/tetrahydrofuran-Identification of a fluxional mixed tetramer

Cyclopropyllithium, C₃ H₅ Li (1), was studied in the presence of one equivalent lithium bromide (LiBr) in diethylether (DEE)/tetrahydrofuran (THF) mixtures and in THF as solvents. Increasing the THF concentration in DEE/THF leads in the ⁶ Li NMR spectrum to a main signal (S1) at δ0.85 (rel. to ext. LiBr/THF) and a second resonance (S2) at δ0.26 aside from a minor component at δ0.07. In pure THF, the ratio of these signals was 66: 28:6. ⁶ Li and ¹³ C NMR allowed to identify the main signal as belonging to a mixed dimer, 1•LiBr, and the signal at 0.26 ppm to a fluxional mixed tetramer, 1₂ •(LiBr)₂ . ¹ J(¹³ C,⁶ Li) coupling constants of 11.0 and 9.8 Hz were measured at 168 K for S1 and S2, respectively, and chemical exchange between both signals was detected by 2D ⁶ Li,⁶ Li exchange spectroscopy and analyzed by temperature-dependent 1D ⁶ Li line-shape calculations. These yielded the equilibrium constants K_eq for the chemical exchange Li₄ (C₃ H₅ )₂ Br₂ ⇌ 2 Li₂ C₃ H₅ Br. Their temperature dependence leads to van't Hoff parameters of ΔH° = 4.6 kJ/mol, ΔS° = 41.4 J/mol K, and ΔG°₂₉₈ = -7.8 kJ/mol. From the rate constants k, Eyring parameters of ΔH^* = 42.0 kJ/mol, ΔS^* = 33.0 J/mol K, and ΔG^*₂₉₈ = 32.2 kJ/mol were calculated for the forward reaction Li₄ (C₃ H₅ )₂ Br₂ → 2 Li₂ C₃ H₅ Br and ΔH^* = 37.5 kJ/mol, ΔS^* = -8.4 J/mol K, and ΔG^*₂₃₈ = 40.0 kJ/mol for the reverse reaction 2Li₂ C₃ H₅ Br → Li₄ (C₃ H₅ )₂ Br₂ .

Direct Addition of Amides to Glycals Enabled by Solvation-Insusceptible 2-Haloazolium Salt Catalysis

The direct 2-deoxyglycosylation of nucleophiles with glycals leads to biologically and pharmacologically important 2-deoxysugar compounds. Although the direct addition of hydroxyl and sulfonamide groups have been well developed, the direct 2-deoxyglycosylation of amide groups has not been reported to date. Herein, we show the first direct 2-deoxyglycosylation of amide groups using a newly designed Brønsted acid catalyst under mild conditions. Through mechanistic investigations, we discovered that the amide group can inhibit acid catalysts, and the inhibition has made the 2-deoxyglycosylation reaction difficult. Diffusion-ordered two-dimensional NMR spectroscopy analysis implied that the 2-chloroazolium salt catalyst was less likely to form aggregates with amides in comparison to other acid catalysts. The chlorine atom and the extended π-scaffold of the catalyst played a crucial role for this phenomenon. This relative insusceptibility to inhibition by amides is more responsible for the catalytic activity than the strength of the acidity.

Extraction of Reliable Molecular Information from Diffusion NMR Spectroscopy: Hydrodynamic Volume or Molecular Mass?

Measuring accurate translational self-diffusion coefficients (D_t ) by NMR techniques with modern spectrometers has become rather routine. In contrast, the derivation of reliable molecular information therefrom still remains a nontrivial task. In this paper, two established approaches to estimating molecular size in terms of hydrodynamic volume (V_H ) or molecular weight (M) are compared. Ad hoc designed experiments allowed the critical aspects of their application to be explored by translating relatively complex theoretical principles into practical take-home messages. For instance, comparing the D_t values of three isosteric Cp₂ MCl₂ complexes (Cp=cyclopentadienyl, M=Ti, Zr, Hf), having significantly different molecular mass, provided an empirical demonstration that V_H is the critical molecular property affecting D_t . This central concept served to clarify the assumptions behind the derivation of D_t =ƒ(M) power laws from the Stokes-Einstein equation. Some pitfalls in establishing log (D_t ) versus log (M) linear correlations for a set of species have been highlighted by further investigations of selected examples. The effectiveness of the Stokes-Einstein equation itself in describing the aggregation or polymerization of differently shaped species has been explored by comparing, for example, a ball-shaped silsesquioxane cage with its cigar-like dimeric form, or styrene with polystyrene macromolecules.

Coinage metal complexes of selenoureas derived from N-heterocyclic carbenes

The coordination chemistry of selenoureas derived from N-heterocyclic carbenes with copper and silver is explored, and compared to previous work with gold.

Aggregation and Solvation of n-Butyllithium

Solution characterizations and ligand binding constants were determined for n-butyllithium in hydrocarbon and ethereal solvents using diffusion-ordered NMR. In hydrocarbon solvents, n-butyllithium exists primarily as an octamer at -40 °C and deaggregates to a hexamer when the temperature is increased. In the presence of THF or diethyl ether, n-butyllithium exists predominantly as a tetra-solvated tetramer and deaggregates to a tetra-solvated dimer in the presence of a large excess or neat THF. The ligand binding constants for the tetra-solvated tetramers were measured using ¹H NMR/DOSY titration.

The Two Alternative Rate-Determining Steps in Benzylic Lithiation Reactions of Esters and Carbamates

Lithiation reactions of tertiary benzylic esters and carbamates have been studied. Kinetic methodology revealed that a two-step reaction pathway should be considered for these reactions, where either the lithium precomplexation and/or the proton transfer steps can be rate determining. Kinetic isotopic effects were evaluated by comparison of the lithiations of the corresponding protio/deutero substrates, and the results obtained support the notion that lithium precomplexation is taking place on the reaction pathway and that it is the rate-determining step in this transformation.

Structural Diversity in Alkali Metal and Alkali Metal Magnesiate Chemistry of the Bulky 2,6-Diisopropyl-N-(trimethylsilyl)anilino Ligand

Bulky amido ligands are precious in s-block chemistry, since they can implant complementary strong basic and weak nucleophilic properties within compounds. Recent work has shown the pivotal importance of the base structure with enhancement of basicity and extraordinary regioselectivities possible for cyclic alkali metal magnesiates containing mixed n-butyl/amido ligand sets. This work advances alkali metal and alkali metal magnesiate chemistry of the bulky arylsilyl amido ligand [N(SiMe3 )(Dipp)]- (Dipp=2,6-iPr2 -C6 H3 ). Infinite chain structures of the parent sodium and potassium amides are disclosed, adding to the few known crystallographically characterised unsolvated s-block metal amides. Solvation by N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) or N,N,N',N'-tetramethylethylenediamine (TMEDA) gives molecular variants of the lithium and sodium amides; whereas for potassium, PMDETA gives a molecular structure, TMEDA affords a novel, hemi-solvated infinite chain. Crystal structures of the first magnesiate examples of this amide in [MMg{N(SiMe3 )(Dipp)}2 (μ-nBu)]∞ (M=Na or K) are also revealed, though these breakdown to their homometallic components in donor solvents as revealed through NMR and DOSY studies.

Radical Cyclisation of α-Halo Aluminium Acetals: A Mechanistic Study

α-Bromo aluminium acetals are suitable substrates for Ueno-Stork-like radical cyclisations affording γ-lactols and acid-sensitive methylene-γ-lactols in high yields. The mechanistic study herein sets the scope and limitation of this reaction. The influence of the halide (or chalcogenide) atom X (X=Cl, Br, I, SPh, SePh) in the precursors α-haloesters, as well as influence of the solvent and temperature was studied. The structure of the aluminium acetal intermediates resulting from the reduction of the corresponding α-haloesters has been investigated by low-temperature (13) C-INEPT diffusion-ordered NMR spectroscopy (DOSY) experiments and quantum calculations, providing new insights into the structures of these thermally labile intermediates. Oxygen-bridged dimeric structures with a planar Al2 O2 ring are proposed for the least hindered aluminium acetals, while monomeric structures seem to prevail for the most hindered species. A comparison against the radical cyclisation of aluminium acetals derived from allyl and propargyl alcohols with the parent Ueno-Stork has been made at the BHandHLYP/6-311++G(d,p) level of theory, highlighting mechanistic similarities and differences.

Separation and quantification of lactate and lipid at 1.3 ppm by diffusion-weighted magnetic resonance spectroscopy

PURPOSE

To separate the spectrally overlapped lactate and lipid signals at 1.3 ppm using diffusion-weighted magnetic resonance spectroscopy (DW-MRS) based on their large diffusivity difference.

METHODS

DW-MRS was applied to the gel phantoms containing lactate and lipid droplets, and to the rat brain tumors. Lactate and lipid signals and their apparent diffusion coefficients were computed from the diffusion-weighted proton spectra. Biexponential fitting and direct spectral subtraction approaches were employed and compared.

RESULTS

DW-MRS could effectively separate lactate and lipid signals both in phantoms and rat brain C6 glioma by biexponential fitting. In phantoms, lactate and lipid signals highly correlated with the known lactate concentration and lipid volume fractions. In C6 glioma, both lactate and lipid signals were detected, and the lipid signal was an order of magnitude higher than lactate signal. The spectral subtraction approach using three diffusion weightings also allowed the separation of lactate and lipid signals, yielding results comparable to those by the biexponential fitting approach.

CONCLUSION

DW-MRS presents a new approach to separate and quantify spectrally overlapped molecules and/or macromolecules, such as lactate and lipid, by using the diffusivity difference associated with their different sizes or mobility within tissue microstructure. Magn Reson Med 77:480-489, 2017. © 2016 International Society for Magnetic Resonance in Medicine.

Base or nucleophile? DFT finally elucidates the origin of the selectivity between the competitive reactions triggered by MeLi or LDA on propanal

The competition between basicity and nucleophilicity of two standard organolithium reagents was studied using DFT. Comparing the reactivity of solvated (MeLi)2 and (LDA)2 toward propanal finally explains why methyllithium adds onto the carbonyl while LDA deprotonates the α-position, in accord with experiment and Ireland's deprotonation TS.

Accurate molecular weight determination of small molecules via DOSY-NMR by using external calibration curves with normalized diffusion coefficients

Determination of the aggregation and solvation numbers of organometallic complexes in solution is an important task to increase insight in reaction mechanisms. Thus knowing which aggregates are formed during a reaction is of high interest to develop better selectivity and higher yields. Diffusion-ordered spectroscopy (DOSY), which separates NMR signals according to the diffusion coefficient, finds increasing use to identify species in solution. However, there still is no simple relationship between diffusion coefficient and molecular weight (MW). Some methods have been developed to estimate the MW but still with a significant error of ±30%. Here we describe a novel development of MW-determination by using an external calibration curve (ECC) approach with normalized diffusion coefficients. Taking the shape of the molecules into account enables accurate MW-predictions with a maximum error of smaller than ±9%. Moreover we show that the addition of multiple internal references is dispensable. One internal reference (that also can be the solvent) is sufficient. If the solvent signal is not accessible, 16 other internal standards (aliphatics and aromatics) are available to avoid signal overlapping problems and provide flexible choice of analytes. This method is independent of NMR-device properties and diversities in temperature or viscosity and offers an easy and robust method to determine accurate MWs in solution.

The Donor-Base-Free Aggregation of Lithium Diisopropyl Amide in Hydrocarbons Revealed by a DOSY Method

Lithium diisopropyl amide (LDA) is a very prominent reagent that plays a key role in organic synthesis, serving as a base par excellence for a broad range of deprotonation reactions. However, the state of aggregation in solution in the absence of donor bases was unclear. In this paper we solved this problem by employing DOSY NMR experiments based on a newly elaborated external calibration curve (ECC) approach with normalized diffusion coefficients.

A pheromone analogue affects the evaporation rate of (+)-disparlure in Lymantria dispar

BACKGROUND

The gypsy moth Lymantria dispar L. is a widespread pest that causes economic damage to cork oak forests. Females produce the sex pheromone (+)-(7R,8S)-epoxy-2-methyloctadecane, known as (+)-disparlure [(+)D], for long-distance attraction of conspecific males. A (+)D analogue, 2-decyl-1-oxaspiro[2.2]pentane (OXP-01), neither stimulating nor attractive by itself, causes short-time inhibition of male response in a 1:1 blend with (+)D. The authors investigated whether and how the biological activity of the natural pheromone is affected by OXP-01 on a long-time basis (up to 16 days), also by looking at possible physicochemical reciprocal interactions.

RESULTS

Blending of (+)D with OXP-01 decreased, under low evaporation rate, the pheromone effectiveness, as assessed by electroantennogram recordings. In male trappings, within the first 24 h, OXP-01 decreased and later enhanced the blend attractiveness, but only under high evaporation rate. Gas chromatography-mass spectroscopy indicates that quantitative retrieval of (+)D from blend cartridges is higher than for pure pheromone, and nuclear magnetic resonance measurements show that OXP-01 produces, possibly by Van der Waals interactions, a bimolecular entity with pheromone causing retention and lengthening of its attractiveness over time.

CONCLUSION

The biological and physicochemical interactions between (+)D and OXP-01 may provide valuable information for the optimisation of pheromone-based control strategies for gypsy moths.

Pre-inverse-crowns: synthetic, structural and reactivity studies of alkali metal magnesiates primed for inverse crown formation

The synthesis, structure and reactivity of donor-free sodium and potassium magnesiates are assessed culminating in the unique 1,4-dimetallation of naphthalene.

Enediolate-dilithium amide mixed aggregates in the enantioselective alkylation of arylacetic acids: structural studies and a stereochemical model

A combination of X-ray crystallography, (6)Li, (15)N, and (13)C NMR spectroscopies, and density functional theory computations affords insight into the structures and reactivities of intervening aggregates underlying highly selective asymmetric alkylations of carboxylic acid dianions (enediolates) mediated by the dilithium salt of a C2-symmetric chiral tetraamine. Crystallography shows a trilithiated n-butyllithium-dilithiated amide that has dimerized to a hexalithiated form. Spectroscopic studies implicate the non-dimerized trilithiated mixed aggregate. Reaction of the dilithiated amide with the dilithium enediolate derived from phenylacetic acid affords a tetralithio aggregate comprised of the two dianions in solution and the dimerized octalithio form in the solid state. Computational studies shed light on the details of the solution structures and afford a highly predictive stereochemical model.

Evaluating cis-2,6-dimethylpiperidide (cis-DMP) as a base component in lithium-mediated zincation chemistry

Most recent advances in metallation chemistry have centred on the bulky secondary amide 2,2,6,6-tetramethylpiperidide (TMP) within mixed metal, often ate, compositions. However, the precursor amine TMP(H) is rather expensive so a cheaper substitute would be welcome. Thus this study was aimed towards developing cheaper non-TMP based mixed-metal bases and, as cis-2,6-dimethylpiperidide (cis-DMP) was chosen as the alternative amide, developing cis-DMP zincate chemistry which has received meagre attention compared to that of its methyl-rich counterpart TMP. A new lithium diethylzincate, [(TMEDA)LiZn(cis-DMP)Et₂] (TMEDA=N,N,N′,N′-tetramethylethylenediamine) has been synthesised by co-complexation of Li(cis-DMP), Et₂Zn and TMEDA, and characterised by NMR (including DOSY) spectroscopy and X-ray crystallography, which revealed a dinuclear contact ion pair arrangement. By using N,N-diisopropylbenzamide as a test aromatic substrate, the deprotonative reactivity of [(TMEDA)LiZn(cis-DMP)Et₂] has been probed and contrasted with that of the known but previously uninvestigated di-tert-butylzincate, [(TMEDA)LiZn(cis-DMP)tBu₂]. The former was found to be the superior base (for example, producing the ortho-deuteriated product in respective yields of 78 % and 48 % following D₂O quenching of zincated benzamide intermediates). An 88 % yield of 2-iodo-N,N-diisopropylbenzamide was obtained on reaction of two equivalents of the diethylzincate with the benzamide followed by iodination. Comparisons are also drawn using 1,1,1,3,3,3-hexamethyldisilazide (HMDS), diisopropylamide and TMP as the amide component in the lithium amide, Et₂Zn and TMEDA system. Under certain conditions, the cis-DMP base system was found to give improved results in comparison to HMDS and diisopropylamide (DA), and comparable results to a TMP system. Two novel complexes isolated from reactions of the di-tert-butylzincate and crystallographically characterised, namely the pre-metallation complex [{(iPr)₂N(Ph)C=O}LiZn(cis-DMP)tBu₂] and the post-metallation complex [(TMEDA)Li(cis-DMP){2-[1-C(=O)N(iPr)₂]C₆H₄}Zn(tBu)], shed valuable light on the structures and mechanisms involved in these alkali-metal-mediated zincation reactions. Aspects of these reactions are also modelled by DFT calculations.

Characterization of cyclopentyllithium and cyclopentyllithium tetrahydrofuran complex

The solid-state structures of unsolvated, hexameric cyclopentyllithium and tetrameric cyclopentyllithium tetrahydrofuran solvate were determined by single-crystal X-ray diffraction. Cyclopentyllithium easily crystallized in hydrocarbon solvents. Solution-state structural analyses of cyclopentyllithium and cyclopentyllithium-tetrahydrofuran complexes in toluene-d8 were also carried out by diffusion-ordered NMR spectroscopy with diffusion coefficient-formula weight correlation analyses and other one- and two-dimensional NMR techniques. The solution-state studies suggest that unsolvated cyclopentyllithium exists as hexamer and tetramer equilibrating with each other. Upon solvation with tetrahydrofuran, cyclopentyllithium exists mostly as a tetrahydrofuran tetrasolvated tetramer.

Oxidation-proof microemulsions: Microstructure and reactivity in the presence of dioxiranes

Dioxiranes are used as reagents in a myriad of synthetically useful oxidations performed in aqueous medium. To extend such an approach also to substrates that are highly hydrophobic, we propose here the use of microemulsions based on the surfactant hexadecyltrimethylammonium hydrogen sulphate (CTAHS) because of its high stability against peroxide species. In this paper, we examine the dioxirane (isolated or generated in situ) reactivity in different CTAHS microemulsions. Yield and selectivity of the oxidation of β-methylstyrene by dimethyldioxirane (DDO) generate "in situ" and of laurolactam by isolated methyl(trifluorometyl)dioxirane (TFDO) were studied. For each microemulsion, the aggregate size and the localization of the components were determined by a combination of NMR and light scattering techniques. The hydrodynamic radius of the micelles is close to the length of the surfactant and this suggests they are spherical in shape. When acetone (the precursor of DDO) is present in the formulation, it partitions itself between the aqueous bulk and the micellar palisade so that the dioxirane eventually formed is readily available to oxidize substrates secluded in the micelle. Apolar substrates, confined within the micelles, are protected from uncontrolled oxidations, leading to an astonishing high selectivity of oxidation of laurolactam to 12-nitro-lauric acid by TFDO. This opens the way to an easy procedure (performed in water under mild conditions) to synthetize ω-nitroacids.