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.

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.

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

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.

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.

Synthesis of an Enantiomerically Pure Inherently Chiral Calix[4]Arene Phosphonic Acid and Its Evaluation as an Organocatalyst.

A facile method for the preparation of enantiomerically pure inherently chiral calix[4]arene phosphonic acid (cR,pR)-7 in four steps starting from the readily available and previously synthesized (cS)-enantiomer of calix[4]arene acetic acid 1 or its methyl ester 2 was developed. The first tests of this unique calixarene Brönsted acid with inherent chirality in organocatalysis of the aza-Diels-Alder reaction of imines with Danishefsky's diene and epoxide ring opening by benzoic acid were performed. The calixarene phosphonic acid (cR,pR)-7 shows good catalytic activities but with low enantioselectivities in these reactions.

Triangles and Squares for a Unique Molecular Crystal Structure: Unsupported Two-Coordinate Lithium Cations and CC Agostic Interactions in Cyclopropyllithium Derivatives.

Understanding and controlling the aggregation state is germane to alkyllithium chemistry. Lewis base-free alkyllithium compounds normally form tetrahedral tetramers or octahedral hexamers in the solid state with the lithium cations being three-coordinate. We report that the unsupported cyclopropyl derivative 1-(trimethylsilyl)cyclopropyllithium [{µ-c-C(SiMe3 )C2 H4 }Li]4 (1), synthesized by the reduction of 1-(phenylthio)-1-(trimethylsilyl)cyclopropane, crystallizes as a tetramer in the space group I-4 with the two-coordinate lithium atoms forming a square. CC agostic interactions complete the coordination sphere around each lithium. The aggregate is preserved in hydrocarbon solution. Furthermore, CC agostic interactions compete intra- and intermolecularly with Lewis base donation as in the unsaturated dimer of 1-(phenylthio)cyclopropyllithium [Li(thf)2 {µ-c-C(SPh)C2 H4 }2 Li (thf)] (3) which is also fully characterized.

The simple production of nonsymmetric quaterpyridines through Kröhnke pyridine synthesis.

Quaterpyridines have been demonstrated to be useful building blocks in metallo-supramolecular chemistry; however, their synthesis requires the preparation of sensitive building blocks. We present here three examples of nonsymmetric quaterpyridines that were easily obtained in yields of 70-85% by condensation of commercially available enones with 6-acetyl-2,2':6',2''-terpyridine through a Kröhnke pyridine synthesis. Easy access to 6-acetyl-2,2':6',2''-terpyridine starting from 2,6-diacetylpyridine and 2-acetylpyridine is described. The X-ray analysis of a chiral quaterpyridine and its Pt(II) complex is presented.

(1R,4R,6S,7R)-5,5-Di-bromo-1,4,8,8-tetra-methyl-tri-cyclo-[5.4.1.0(4,6)]dodecan-12-one.

The title compound, C16H24Br2O, was synthesized from the reaction of ß-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from Atlas cedar (Cedrus atlantica). The asymmetric unit contains two independent mol-ecules with similar conformations. Each mol-ecule is built up from two fused seven-membered rings and an additional three-membered ring. In both mol-ecules, one of the seven-membered rings has a chair conformation, whereas the other displays a screw-boat conformation.

A one-dimensional polymeric cobalt(III)-potassium complex with 18-crown-6, cyanide and porphyrinate ligands.

The reaction of Co(II)(TpivPP) {TpivPP is the dianion of 5,10,15,20-tetra-kis-[2-(2,2-di-methyl-propanamido)-phen-yl]por-ph-yrin} with an excess of KCN salts and an excess of the 18-crown-6 in chloro-benzene leads to the polymeric title compound catena-poly[[dicyanido-2κ(2) C-(1,4,7,10,13,16-hexa-oxa-cyclo-octa-decane-1κ(6) O){µ3-(2α,2ß)-5,10,15,20-tetra-kis-[2-(2,2-di-methyl-propanamido)-phen-yl]porphyrinato-1κO (5):2κ(4) N,N',N'',N''':1'κO (15)}cobalt(III)potassium] dihydrate], {[CoK(CN)2(C12H24O6)(C64H64N8O4]·2H2O} n . The Co(III) ion lies on an inversion center, and the asymmetric unit contains one half of a [Co(III)(2α,2ß-TpivPP)(CN)2](-) ion complex and one half of a [K(18-C-6](+) counter-ion (18-C-6 is 1,4,7,10,13,16-hexa-oxa-cyclo-octa-deca-ne), where the K(I) ion lies on an inversion center. The Co(III) ion is hexa-coordinated by two C-bonded axial cyanide ligands and the four pyrrole N atoms of the porphyrin ligand. The K(I) ion is chelated by the six O atoms of the 18-crown-6 mol-ecule and is further coordinated by two O atoms of pivalamido groups of the porphyrin ligands, leading to the formation of polymeric chains running along [011]. In the crystal, the polymeric chains and the lattice water mol-ecules are linked by N-H⋯O and O-H⋯N hydrogen bonds, as well as weak C-H⋯O, O-H⋯π and C-H⋯π inter-actions into a three-dimensional supra-molecular architecture.

(1R,3S,8R)-3,7,7,10-Tetra-methyl-tri-cyclo-[6.4.0.0(1,3)]dodec-9-en-11-one.

The absolute configuration of the title compound, C16H24O, has been deduced from the chemical pathway. The six-membered ring has a roughly half-chair conformation with the quaternary C atom as the flap. The seven-membered ring displays a chair conformation. In the crystal, there is a weak C-H⋯O hydrogen bond between the methyl-ene group of the cyclo-propane ring and the carbonyl group of a screw-axis-related mol-ecule, which builds up a zigzag-like chain along the b-axis direction.

(4bS,8aS)-1-Isopropyl-4b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octa-hydro-phenan-thren-2-yl benzoate.

The title compound, C27H34O2, was hemisynthesized through direct benzoyl-ation of the naturally occurring meroterpene totarol. The central fused six-membered ring has a half-chair conformation, whereas the terminal six-membered ring displays a chair conformation. The dihedral angle between the fused benzene ring and the benzoyl benzene ring is 73.05 (14)°. The S,S chirality of the mol-ecule is consistent with the synthetic pathway, and confirmed by the refinement of the Flack parameter.

(1S,3S,8R,9S,10R)-9,10-Ep-oxy-3,7,7,10-tetra-methyl-tri-cyclo-[6.4.0.0(1,3)]dodeca-ne.

The title compound, C16H26O, was synthesized by treating (1S,3S,8R)-3,7,7,10-tetra-methyl-tri-cyclo-[6.4.0.0(1,3)]dodec-9-ene with meta-chloro-perbenzoic acid. The mol-ecule is built up from two fused six- and seven-membered rings. The six-membered ring has a half-chair conformation, whereas the seven-membered ring displays a boat conformation. In the crystal, there are no significant intermolecular interactions present.

(4bS,8aS)-1-Isopropyl-4b,8,8-trimethyl-4b,5,6,7,8,8a,9,10-octa-hydro-phenan-thren-2-yl acetate.

The hemisynthesis of the title compound, C22H32O2, was carried out through direct acetyl-ation reaction of the naturally occurring diterpene totarol [systematic name: (4bS,8aS)-4b,8,8-trimethyl-1-propan-2-yl-5,6,7,8a,9,10-hexa-hydro-phen-an-thren-2-ol]. The mol-ecule is built up from three fused six membered rings, one saturated and two unsaturated. The central unsaturated ring has a half-chair conformation, whereas the other unsaturated ring displays a chair conformation. The absolute configuration is deduced from the chemical pathway. The value of the Hooft parameter [-0.10 (6)] allowed this absolute configuration to be confirmed.

(1S,3R,8R,10R)-2,2-Di-bromo-3,7,7,10-tetra-methyl-tri-cyclo-[6.4.0.0(1,3)]dodecan-9-one.

The title compound, C16H24Br2O was synthesized by three steps from ß-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from essential oil of the Atlas cedar (Cedrus atlantica). The mol-ecule is built up from a seven-membered ring to which a six- and a three-membered ring are fused. The six-membered ring shows a chair conformation. One C atom in the seven-membered ring and two methyl groups attached to the ring are disordered over two sets of sites, with an occupancy ratio of 0.658 (7):0.342 (7).

Aqua-(5,10,15,20-tetra-phenyl-porphyrin-ato-κ(4) N)cadmium(II)-18-crown-6 (1/1).

The title compound, [Cd(C44H28N4)(H2O)]·(C12H24O6), was made by the reaction of the [Cd(TPP)] with an excess of 18-crown-6 in chloro-benzene (where TPP is tetra-phenyl-porphyrinate). The Cd(II) cation is chelated by a TPP anion and coordinated by a water mol-ecule in a distorted N4O square-pyramidal geometry, the Cd(II) cation being displaced by 0.7533 (9) Šfrom the mean plane of four N atoms of TPP anion. The porphyrin core presents a significant distortion, the maximum atomic deviation from the 24-atom mean plane is 0.1517 (2) Å. The 18-crown-6 mol-ecule is linked with the Cd(II) complex via classical O-H⋯O hydrogen bonds. In the crystal, weak C-H⋯π inter-actions link the complex and 18-crown-6 mol-ecules into a three-dimensional supra-molecular architecture.

Diaqua-(5,10,15,20-tetra-phenyl-porphyrinato-κ(4)N)magnesium-18-crown-6 (1/1).

In the title compound, [Mg(C(44)H(28)N(4))(H(2)O)(2)]·C(12)H(24)O(6), the Mg(II) cation lies on an inversion center and is octa-hedrally coordinated by the four N atoms of the deprotonated tetra-phenyl-porphyrin (TPP) ligand and by two water mol-ecules. The asymmetric unit contains one half of the [Mg(TPP)(H(2)O)(2)] complex and one half of an 18-crown-6 mol-ecule. The average equatorial magnesium-pyrrole N atom distance (Mg-N(p)) is 2.071 (1) Šand the axial Mg-O(H(2)O) bond length is 2.213 (1) Å. The crystal packing is stabilized by two O-H⋯O hydrogen bonds between coordinating water mol-ecules and adjacent 18-crown-6 mol-ecules, and exhibits a one-dimensional supramolecular structure along the a axis. The supramolecular architecture is futher stabilized by weak C-H⋯π inter-actions. The 18-crown-6 mol-ecule is disordered over two sets of sites with an occupancy ratio of 0.8:0.2.

(1S,3R,8R)-2,2-Di-chloro-3,7,7,10-tetra-methyl-tri-cyclo-[6.4.0.0(1,3)]dodec-9-en-11-one.

The title compound, C16H22Cl2O, was synthesized from ß-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The mol-ecule is built up from fused six- and seven-membered rings and an additional three-membered ring arising from the reaction of himachalene with di-chloro-carbene. The six-membered ring has an envelope conformation, with the C atom belonging to the three-membered ring forming the flap, whereas the seven-membered ring displays a screw-boat conformation; the dihedral angle between the rings (all atoms) is 59.65 (14)°.

Bis(cinnamato-κO)(1,10-phenanthroline-κ(2) N,N')copper(II).

The title mononuclear Cu(II) complex, [Cu(C9H7O2)2(C12H8N2)], is comprised of a Cu(II) cation, two cinnamate (L (-)) ligands and a 1,10-phenanthroline (phen) ligand. The Cu(II) atom and phen ligand lie on a twofold rotation axis. The Cu(II) atom is coordinated by two O atoms from two carboxyl-ate groups of two (L (-)) ligands and two N atoms from one phen ligand, exhibiting a distorted square-planar geometry. In the crystal, mol-ecules are assembled into supra-molecular chains parallel to the c axis through weak C-H⋯O hydrogen bonds involving the phen and cinnamate ligands.