New Protocol for the Synthesis of S-Thioesters from Benzylic, Allylic and Tertiary Alcohols with Thioacetic Acid.

A new one-pot solvent-less reaction to convert benzylic, allylic, ferrocenyl or tertiary alcohols into S-thioesters, bench-stable and less odorous precursors of the corresponding thiols, which is based on reactions in neat thioacetic acid in the presence of tetrafluoroboric acid, is presented. Reaction monitoring by NMR and GC of the benzyl alcohol conversion indicated the intermediate formation of benzyl acetate and benzyl thionoacetate (PhCH2 OC(S)CH3 ) prior to the slower conversion to the final S-benzyl thioacetate product. Increasing the HBF4 concentration enhanced the reaction rate, giving good to excellent yield (up to 99 %) for a large scope of alcohols. Control experiments, with support of DFT calculations, have revealed a thermodynamically favorable, though requiring HBF4 -activation, disproportionation of CH3 C(O)SH to CH3 C(O)OH and CH3 C(S)SH, the latter immediately decomposing to H2 S and (MeC)4 S6 but also generating the hitherto unreported [MeC(O)C(Me)S]2 (µ-S)2 . Kinetic investigations demonstrated that the rate of benzyl alcohol conversion is second-order in [PhCH2 OH] and second order in [HBF4 ], while the rate of conversion of the benzyl acetate intermediate to S-benzyl thioacetate is second order in [PhCOOMe] and fourth order in [HBF4 ]. The DFT calculations rationalize the need to two alcohol molecules and two protons to generate the reactive benzyl cation.

Acetate exchange mechanism on a Zr12 oxo hydroxo cluster: relevance for reshaping Zr-carboxylate coordination adaptable networks.

The kinetics and mechanism of the acetate ligand exchange with free acetic acid in [Zr6O4(OH)4(O2CCH3)12]2, used as a molecular model of crosslink migration in [Zr6O4(OH)4(carboxylate)12-n(OH)n]-based coordination adaptable networks with vitrimer-like properties, has been thoroughly investigated by dynamic 1H NMR and DFT calculations. The compound maintains its C2h-symmetric Zr12 structure in CD2Cl2 and C6D6, while it splits into its Zr6 subunits in CD3OD and D2O. In the Zr12 structure, the topologically different acetates (3 chelating, 6 belt-bridging, 2 intercluster-bridging and 1 inner-face-bridging) of the Zr6 subunits behave differently in the presence of free CH3COOH: very fast exchange for the chelating (coalesced resonance at room temperature), slower exchange for the belt-bridging (line broadening upon warming), no observable exchange up to 65 °C (by EXSY NMR) for the intercluster- and inner-face-bridging. The rates of the first two exchange processes have zero-order dependence on [CH3COOH]. Variable-temperature line broadening studies yielded ΔH‡ = 15.0 ± 0.4 kcal mol-1, ΔS‡ = 8 ± 1 cal mol-1 K-1 (-30 to +25 °C range in CD2Cl2) for the chelating acetates and ΔH‡ = 22.7 ± 1.6, 22.9 ± 2.1 and 20.6 ± 1.0 kcal mol-1 and ΔS‡ = 13 ± 5, 14 ± 6 and 9 ± 3 cal mol-1 K-1, respectively (+25 to +70 °C range in C6D6), for three distinct resonances of magnetically inequivalent belt-bridging acetates. With support of DFT calculations, these results point to an operationally associative mechanism involving a rate-determining partial dissociation to monodentate acetate, followed by rapid acid coordination and proton transfer. The cluster µ3-OH ligands accelerate the exchange processes through H-bonding stabilization of the coordinatively unsaturated intermediate. The lower exchange barrier for the chelated vs. bridging acetates is associated to the release of ring strain. The results presented in this investigation may help the interpretation of carboxylate exchange phenomena in other systems and the design of new carboxylate-based materials.

A mononuclear cobalt(III) carboxylate complex with a fully O-based coordination sphere: CoIII-O bond homolysis and controlled radical polymerisation from [Co(acac)2(O2CPh)].

The addition of benzoyl peroxide to [CoII(acac)2] in a 1 : 2 ratio selectively produces [CoIII(acac)2(O2CPh)], a diamagnetic (NMR) mononuclear CoIII complex with an octahedral (X-ray diffraction) coordination geometry. It is the first reported mononuclear CoIII derivative with a chelated monocarboxylate ligand and an entirely O-based coordination sphere. The compound degrades in solution quite slowly by homolytic CoIII-O2CPh bond cleavage upon warming above 40 °C to produce benzoate radicals and can serve as a unimolecular thermal initiator for the well-controlled radical polymerisation of vinyl acetate. Addition of ligands (L = py, NEt3) induces benzoate chelate ring opening and formation of both cis and trans isomers of [CoIII(acac)2(O2CPh)(L)] for L = py under kinetic control, then converting quantitatively to the cis isomer, whereas the reaction is less selective and equilibrated for L = NEt3. The py addition strengthens the CoIII-O2CPh bond and lowers the initiator efficiency in radical polymerisation, whereas the NEt3 addition results in benzoate radical quenching by a redox process. In addition to clarifying the mechanism of the radical polymerisation redox initiation by peroxides and rationalizing the quite low efficiency factor for the previously reported [CoII(acac)2]/peroxide-initiated organometallic-mediated radical polymerisation (OMRP) of vinyl acetate, this investigation provides relevant information on the CoIII-O homolytic bond cleavage process.

Synthesis and crystal structure of [(Sp )-(2-phenyl-ferrocen-yl)meth-yl]tri-methyl-ammonium iodide di-chloro-methane monosolvate.

As a follow-up to our research on the chemistry of disubstituted ferrocene derivatives, the synthesis and the structure of the title compound, [Fe(C5H5)(C15H19N)]I·CH2Cl2, is described. The cation mol-ecule is built up from a ferrocene disubstituted by a tri-methyl-ammonium methyl group and a phenyl ring. The asymmetric unit contains the iodide to equilibrate the charge and a disordered di-chloro-methane solvate. The disordered model results from a roughly statistical exchange (0.6/0.4) between one Cl and one H. The packing of the structure is stabilized by weak C-H⋯X (X = I, Cl), C-H⋯π(Cp) and C-Cl⋯π(phen-yl) inter-actions, building a three-dimensional network. The cation has planar chirality with Sp (Fc) absolute configuration. The structure of the title compound is compared with related disubstituted (tri-meth-ylammonio)-methyl ferrocenes.

Iodine-promoted insertion of the oxygen atom from water in η4-vinylketene[Fe(CO)3] complexes.

Iodine promotes the in situ formation of iron(II) species from η4-vinylketene[Fe(CO)3] (3a-h) as a key intermediate for the synthesis of 2(5H)-furanones (4a-h) by a sequential water-insertion/carbon-oxygen coupling under mild reaction conditions. Compounds 4a-h were obtained in good to excellent yields. A possible reaction pathway was also proposed by DFT calculations. This methodology can be extended to the synthesis of (5H)-pyrrol-2-ones using anilines, with moderate yields and a few limitations.

Interrupted Intramolecular Hydroaminomethylation of N-Protected-2-vinyl Anilines: Novel Access to 3-Substitued Indoles or Indoline-2-ols.

A new synthetic alternative to the synthesis of 3-methyl indoles and 3-methyl indoline-2-ols with an excellent atomic economy is presented in this study. It is demonstrated that the intramolecular interrupted hydroaminomethylation (HAM) reaction is a powerful tool for the formation of these compounds, which exhibit wide-ranging biological activity. Several N-Protected-2-vinyl anilines were synthesized and involved in the reaction producing the corresponding 3-methylindole or 3-methyl indoline-2-ol depending on the nature of the N-protecting groups.

Replacement of Volatile Acetic Acid by Solid SiO2@COOH Silica (Nano)Beads for (Ep)Oxidation Using Mn and Fe Complexes Containing BPMEN Ligand.

Mn and Fe BPMEN complexes showed excellent reactivity in catalytic oxidation with an excess of co-reagent (CH3COOH). In the straight line of a cleaner catalytic system, volatile acetic acid was replaced by SiO2 (nano)particles with two different sizes to which pending carboxylic functions were added (SiO2@COOH). The SiO2@COOH beads were obtained by the functionalization of SiO2 with pending nitrile functions (SiO2@CN) followed by CN hydrolysis. All complexes and silica beads were characterized by NMR, infrared, DLS, TEM, X-ray diffraction. The replacement of CH3COOH by SiO2@COOH (100 times less on molar ratio) has been evaluated for (ep)oxidation on several substrates (cyclooctene, cyclohexene, cyclohexanol) and discussed in terms of activity and green metrics.

Synthesis and crystallographic studies of 2-(di-phenyl-phosphino-thio-yl)-2-(3-oxobut-1-en-yl)ferrocene.

As a follow-up to our research on the chemistry of disubstituted ferrocene derivatives, the synthesis and the structure of the title compound, 2-(di-phenyl-phosphino-thio-yl)-2-(3-oxobut-1-en-yl)ferrocene, [Fe(C5H5)(C21H18OPS)], are described. The mol-ecule is built up from a ferrocene unit disubstituted by an S-protected di-phenyl-phosphine group and by a methyl-vinyl-ketone chain. The crystal structure features weak C-H⋯O and C-H⋯S inter-actions, which build a two-dimensional network. This structure is compared to that of the related disubstituted di-phenyl-phosphino ferrocene.

A new P,S-coordinating ferrocenyl ligand: synthesis of a precursor and its coordination compounds with PdII and PtII. Corrigendum.

In the paper by Mouas Toma et al. [Acta Cryst. (2014), C70, 460-464], there was an error in the name of the first author.

Erratum: rac-{[2-(Diphenyl-thio-phosphor-yl)ferrocen-yl]meth-yl}dimethyl-ammonium diphenyl-dithio-phosphinate. Corrigendum.

[This corrects the article DOI: 10.1107/S1600536812009129.].

Crystal structure of (R)-5-[(R)-3-(4-chloro-phen-yl)-5-methyl-4,5-di-hydro-isoxazol-5-yl]-2-methyl-cyclo-hex-2-enone.

The title compound, C17H18ClNO2, was prepared and isolated as a pure diastereoisomer, using column chromatography followed by a succession of fractional crystallizations. Its exact structure was fully identified via 1H NMR and confirmed by X-ray diffraction. It is built up from a central five-membered di-hydro-isoxazole ring to which a p-chloro-phenyl group and a cyclo-hex-2-enone ring are attached in the 3 and 5 positions. The cyclo-hex-2-one and isoxazoline rings each exhibit an envelope conformation. The crystal packing features C-H⋯O, C-H⋯N and C-H⋯π inter-actions, which generate a three-dimensional network.

Synthesis of S-Alkyl Phosphinocarbodithioates with Switch between P(III) and P(V) Derivatives.

Simple and effective synthetic pathways are described to prepare compounds R2P(X)C(S)SCH(Me)Ph with the P atom either in the oxidation state V [R/X = t-Bu/O (6), Ph/S, (7), t-Bu/S (8), t-Bu/Se (9)] or III [R/X = Ph/BH3 (4), t-Bu/BH3 (5), t-Bu/lone pair (10)]. Compound 9 is the first example of carbodithioate ester with a P = Se group, and for the first time, a phosphinocarboditioate with a free phosphine function (compound 10) is described. Stabilization of the latter crucially depends on the steric protection by the t-Bu groups since an analogous derivative with R = Ph is observable but too unstable for isolation. Compound 10 can be reversibly protonated to yield the [t-Bu2PHC(S)SCH(Me)Ph]+ cation (10-H+), which was isolated as a BF4- salt. A few interconversion processes resulting in the facile addition/removal or exchange of the X group in this family of compounds are also described. The oxidation state of the phosphorus atom and the nature of an electron-withdrawing group have a significant impact on the spectral properties.

A triangular palladium(II) supramolecular coordination complex based on 1,4-bis(1H-imidazol-1-yl)benzene and (2,2'-bipyridyl)palladium(II) nitrate: synthesis and crystal structure.

The self-assembly of ditopic bis(1H-imidazol-1-yl)benzene ligands (LH) and the complex (2,2'-bipyridyl-κ2N,N')bis(nitrato-κO)palladium(II) affords the supramolecular coordination complex tris[µ-bis(1H-imidazol-1-yl)benzene-κ2N3:N3']-triangulo-tris[(2,2'-bipyridyl-κ2N,N')palladium(II)] hexakis(hexafluoridophosphate) acetonitrile heptasolvate, [Pd3(C10H8N2)3(C12H10N4)3](PF6)6·7CH3CN, 2. The structure of 2 was characterized in acetonitrile-d3 by 1H/13C NMR spectroscopy and a DOSY experiment. The trimeric nature of supramolecular coordination complex 2 in solution was ascertained by cold spray ionization mass spectrometry (CSI-MS) and confirmed in the solid state by X-ray structure analysis. The asymmetric unit of 2 comprises the trimetallic Pd complex, six PF6- counter-ions and seven acetonitrile solvent molecules. Moreover, there is one cavity within the unit cell which could contain diethyl ether solvent molecules, as suggested by the crystallization process. The packing is stabilized by weak inter- and intramolecular C-H...N and C-H...F interactions. Interestingly, the crystal structure displays two distinct conformations for the LH ligand (i.e. syn and anti), with an all-syn-[Pd] coordination mode. This result is in contrast to the solution behaviour, where multiple structures with syn/anti-LH and syn/anti-[Pd] are a priori possible and expected to be in rapid equilibrium.

Crystal structure of penta-carbon-yl(2,2-di-fluoro-propane-thio-ato-κS)manganese(I).

The title compound, [Mn{SC(O)CF2CH3}(CO)5], has been isolated as a by-product during the reaction of K[Mn(CO)5] with CH3CF2COCl. It is built up from a di-fluoro-methyl-propane-thio-ate bonded to an Mn(CO)5 moiety through the S atom. The Mn atom has an almost perfect octa-hedral coordination sphere. It is one of the rare examples of compounds containing the (CO)5MnS-C fragment. In the crystal, the methyl group occupies a pocket surrounded by the O atoms of three carbonyl groups of the Mn(CO)5 moiety; however, the H⋯O distances are rather long. These inter-actions lead to the formation of layers lying parallel to (101), which enclose R 4 4(15) and R 4 4(16) ring motifs. The CF2 group is disordered over two sets of sites with occupancies of 0.849 (3) and 0.151 (3).

Fluoroalkyl Radical Generation by Homolytic Bond Dissociation in Pentacarbonylmanganese Derivatives.

Thermal decarbonylation of the acyl compounds [Mn(CO)5 (CORF )] (RF =CF3 , CHF2 , CH2 CF3 , CF2 CH3 ) yielded the corresponding alkyl derivatives [Mn(CO)5 (RF )], some of which have not been previously reported. The compounds were fully characterized by analytical and spectroscopic methods and by several single-crystal X-ray diffraction studies. The solution-phase IR characterization in the CO stretching region, with the assistance of DFT calculations, has allowed the assignment of several weak bands to vibrations of the [Mn(12 CO)4 (eq-13 CO)(RF )] and [Mn(12 CO)4 (ax-13 CO)(RF )] isotopomers and a ranking of the RF donor power in the order CF3

New polysubstituted monoterpenic thiazolidinones: synthesis, spectroscopic and crystal structure studies.

The synthesis of three new polysubstituted monoterpenic thiazolidin-4-ones, namely (Z)-3-methyl-2-{(E)-[(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene]hydrazinylidene}thiazolidin-4-one, C14H21N3OS (2), (2Z,5Z)-5-[(dimethylamino)methylidene]-2-{(E)-[(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene]hydrazinylidene}thiazolidin-4-one, C16H24N4OS (3), and (2Z,5Z)-5-[(dimethylamino)methylidene]-3-methyl-2-{(E)-[(1R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ylidene]hydrazinylidene}thiazolidin-4-one, C17H26N4OS (4), is reported, starting from the corresponding thiosemicarbazones obtained from naturally occurring (R)-camphor. All the newly obtained thiazolidin-4-ones have been fully characterized by HRMS and 1H and 13C (1D and 2D) NMR spectroscopy. Two of them, i.e. 2 and 3, were identified by single-crystal X-ray crystallography, confirming the synthetic pathway and the spectroscopic analyses. In 3, there are two roughly identical molecules within the asymmetric unit with the same absolute configuration. These two molecules are linked through N-H...O hydrogen bonds, building an R22(8) graph-set motif.

A strongly fluorescent NiII complex with 2-(2-hy-droxy-eth-yl)pyridine ligands: synthesis, characterization and theoretical analysis and comparison with a related polymeric CuII complex.

The synthesis and characterization of di-aqua-bis-[2-(2-hy-droxy-eth-yl)pyridine-κ2N,O)nickel(II) dinitrate, [Ni(C7H9NO)2(H2O)2](NO3)2, under ambient conditions is reported and compared with catena-poly[[bis-[2-(2-hy-droxy-eth-yl)pyridine-κ2N,O]copper(II)]-µ-sulfato-κ2O:O'], [Cu(C7H9NO)2(SO4)] n [Zegh-ouan et al. (2016 ▸). Private communication (refcode 1481676). CCDC, Cambridge, England]. In the two complexes, the 2-(2-hy-droxy-eth-yl)pyridine ligands coordinate the metal ions through the N atom of the pyridine ring and the O atom of the hy-droxy group, creating a chelate ring. The NiII or CuII ion lies on an inversion centre and exhibits a slightly distorted MO4N2 octa-hedral coordination geometry, build up by O and N atoms from two 2-(2-hy-droxy-eth-yl)pyridine ligands and two water mol-ecules or two O atoms belonging to sulfate anions. The sulfate anion bridges the CuII ions, forming a polymeric chain. The photoluminescence properties of these complexes have been studied on as-synthesized samples and reveal that both compounds display a strong blue-light emission with maxima around 497 nm. From DFT/TDDFT studies, the blue emission appears to be derived from the ligand-to-metal charge-transfer (LMCT) excited state. In addition, the IR spectroscopic properties and thermogravimetric behaviours of both complexes have been investigated.

The crystal structure of a new ferrocenyl P,N ligand: 1-[(2,2-di-methyl-hydrazin-1-yl-idene)meth-yl]-1'-(di-phenyl-phospho-rothio-yl)ferrocene.

The asymmetric unit of the title compound, [Fe(C8H11N2)(C17H14PS)], contains two independent mol-ecules (A and B) with very similar conformations. Each mol-ecule is built up from a ferrocene unit substituted in the 1 and 1' positions by a protected sulfur di-phenyl-phosphine and by a di-methyl-hydrazine, -C(H)=N-N(CH3)2, fragment. The two independent mol-ecules are linked by a C-H⋯N hydrogen bond. In the crystal, the A-B dimer is linked by a pair of C-H⋯S hydrogen bonds, forming a centrosymmetric four-mol-ecule arrangement. These units are linked by C-H⋯π inter-actions, forming a supra-molecular three-dimensional structure.

Crystal structure of 2-isopropyl-4-meth-oxy-5-methyl-phenyl 4-methyl-benzene-sulfonate.

The title compound, C18H22O4S, an hemisynthetic product, was obtained by the tosyl-ation reaction of the naturally occurring meroterpene p-meth-oxy-thymol. The mol-ecule comprises a tetra-substitued phenyl ring linked to a toluene-sulfonate through one of its O atoms. In the crystal, C-H⋯O and C-H⋯π inter-actions link the mol-ecules, forming a three-dimensional network.

Synthesis and Characterization of the Most Active Copper ATRP Catalyst Based on Tris[(4-dimethylaminopyridyl)methyl]amine.

The tris[(4-dimethylaminopyridyl)methyl]amine (TPMANMe2) as a ligand for copper-catalyzed atom transfer radical polymerization (ATRP) is reported. In solution, the [CuI(TPMANMe2)Br] complex shows fluxionality by variable-temperature NMR, indicating rapid ligand exchange. In the solid state, the [CuII(TPMANMe2)Br][Br] complex exhibits a slightly distorted trigonal bipyramidal geometry (τ = 0.89). The UV-vis spectrum of [CuII(TPMANMe2)Br]+ salts is similar to those of other pyridine-based ATRP catalysts. Electrochemical studies of [Cu(TPMANMe2)]2+ and [Cu(TPMANMe2)Br]+ showed highly negative redox potentials (E1/2 = -302 and -554 mV vs SCE, respectively), suggesting unprecedented ATRP catalytic activity. Cyclic voltammetry (CV) in the presence of methyl 2-bromopropionate (MBrP; acrylate mimic) was used to determine activation rate constant ka = 1.1 × 106 M-1 s-1, confirming the extremely high catalyst reactivity. In the presence of the more active ethyl α-bromoisobutyrate (EBiB; methacrylate mimic), total catalysis was observed and an activation rate constant ka = 7.2 × 106 M-1 s-1 was calculated with values of KATRP ≈ 1. ATRP of methyl acrylate showed a well-controlled polymerization using as little as 10 ppm of catalyst relative to monomer, while side reactions such as CuI-catalyzed radical termination (CRT) could be suppressed due to the low concentration of L/CuI at a steady state.