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.

2-Thiazolines: an update on synthetic methods and catalysis.

2-Thiazolines are important building blocks in organic synthesis and are of great importance in many areas of chemistry. At the end of the last century, the use of 2-thiazolines increased in a significant way, especially in synthesis and catalysis. This review highlights the synthetic and catalytic value of 2-thiazolines in the last two decades. We will discuss the new synthetic methodologies for obtaining these heterocycles including new schemes for accessing their asymmetric versions. Most of the new catalytic applications include a variety of 2-thiazoline ligands containing diverse donor atoms, which in combination with metals like Pd, Ir, and Cu, among others, exhibit remarkable catalytic performances.

Synthesis, characterization, and inhibition effects of a novel eugenol derivative bearing pyrrole functionalities on the corrosion of mild steel in a HCl acid solution.

Semi-synthetic modifications of natural products have yielded numerous anti-cancer drugs, antimicrobials, and corrosion inhibitors. In this study, eugenol, a natural product, was synthetically modified to generate a novel heterocyclic compound: pyrrole, which forms crystals. The latter is the outcome of the condensation reaction between eugenol hydrazide and 2,5-hexanedione, conducted under reflux ethanol conditions, without a catalyst, achieving a 96% yield. This compound structure was characterized through spectroscopic methods, such as NMR and FTIR, and validated par the crystal's X-ray diffraction analysis. According to the findings of the electrochemical study, pyrrole demonstrated effective inhibition against the carbon steel's corrosion in a 1 M HCl acid solution.

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.

New enantiopure palladium(II) complexes from a stereodynamic 2,2'-biphosphole ligand.

Two enantiopure palladium(II) complexes, viz. [1,1'-(butane-1,3-diyl)-3,3',4,4'-tetramethyl-5,5'-diphenyl-2,2'-biphosphole]dichloridopalladium(II) dichloromethane solvate [systematic name: dichlorido(1,2,5,10,11-pentamethyl-3,9-diphenylperhydrodicyclopenta[a,c][1,4]diphosphepine-kappa(2)P,P')palladium(II) dichloromethane solvate], [PdCl2(C28H30P2)] x CH2Cl2, have been synthesized from stereodynamic diphosphines derived from 2,2'-biphosphole through a metal kinetic dynamic resolution. In both structures, the coordination around the metal atom is square planar, with a cis arrangement of the ligands that drastically reduces the dihedral angle between the two phosphole rings compared with the free ligand. The structural determination of both enantiomers unambiguously establishes the absolute configuration of both central and axial elements of chirality of the 2,2'-biphosphole framework and indicates that the original carbon chirality of the backbone controls the chiralities of the 2,2'-biphosphole framework.

Dichlorido[(S,R(S))-1-diphenylphosphino-2-(ethylsulfanylmethyl)ferrocene]palladium(II).

The reaction of enantiomerically pure planar chiral ferrocene phosphine thioether with bis(acetonitrile)dichloridopalladium yields the title square-planar mononuclear palladium complex as an enantiomerically pure single diastereoisomer, [PdFe(C5H5)(C20H20PS)Cl2]. The planar chirality of the ligand is retained in the complex and fully controls the central chirality on the S atom. The absolute configuration, viz. S for the planar chirality and R for the S atom, is unequivocally determined by refinement of the Flack parameter.

Platinum-catalysed intermolecular addition of carbonyl compounds to 1,6-enynes: investigation of a new reaction pathway.

A novel intermolecular addition of aldehydes to 1,6-enynes via a Pt-carbene intermediate provides the diastereoselective formation of valuable tricyclic compounds.

Chirality control in 2,2'-biphosphole ligand leading to enantiopure Pd complex.

Asymmetric alkylation of the 3,4-dimethyl-5-phenyl-2,2'-biphospholyl anion with the (2R,4R)-(-)-pentaneditosylate leads to a new chirally flexible 2,2'-biphosphole ligand as a mixture of three diasteroisomers. By complexation with Pd(II), a chirality control occurs to afford enantiopure Pd complex.

Platinum(II)-phosphole complexes: synthesis and evaluation as enyne cycloisomerisation catalysts.

A series of platinum(II)-monophosphole complexes has been synthesized and used in enyne cycloisomerisations in order to study the effect of the ligand on the catalytic activity and selectivity. Reactions were performed on various N- or C-tethered 1,6-enynes and in the absence or in the presence of nucleophiles. For the most efficient cationic Pt(II)-complexes, it was also evidenced that the counterion and/or the solvent could have an influence on both the efficiency and the selectivity in the competition between the 5-exo-dig and the 6-endo-dig processes.

Novel phospholyl(diphenylphosphino)methane-ruthenium complexes: unexpected non-assisted cis to trans isomerization of [RuCl2(κ(2)-P-P')2].

Using the unsymmetrical P-P' phospholyl(phosphino)methane ligand, complex cis-[RuCl(2)(κ(2)-P-P')(2)] is easily prepared from [RuCl(2)(DMSO)(4)]. The two phosphole-phosphorus atoms lie in the trans position to the two cis-chloro ligands. This complex slowly isomerizes spontaneously at 20 °C to the trans-[RuCl(2)(κ(2)-P-P')(2)] diastereoisomer where the two phosphole moieties are mutually trans, as well as the two chloro ligands and the two Ph(2)P moieties. DFT calculations show that this non-classical cis-trans isomerisation process requires a 3 kcal mol(-1) energy and involves the decoordination of a phosphole arm.

Phosphine-phosphite ligands: chelate ring size vs. activity and enantioselectivity relationships in asymmetric hydrogenation.

A series of new phosphine-phosphite ligands P(C)(n)OP (n = 1-4) have been synthesized and used for rhodium-catalyzed asymmetric hydrogenation of prochiral olefins in order to study the effect of the chelate ring size. Excellent ees (up to 97.5%) were obtained in the hydrogenation of dimethyl itaconate and an increase of activity and enantioselectivity was observed in the hydrogenation of (Z)-α-acetamidocinnamic acid methyl ester with the increasing length of the backbone of the ligands.

Chiral diphosphinites derived from 2,2-biphosphole as a new class of stereodynamic ligands for enantioselective hydrogenation.

New stereodynamic diphosphinites derived from 2,2'-biphosphole, were synthesised by introduction of a linker obtained from chiral diols between the two phosphorus atoms and used for catalytic hydrogenation through a dual chirality control induced by Rh-coordination. The application of these ligands in hydrogenation of dimethyl itaconate shows that the enantioselectivity strongly depends on steric and electronic properties of the chiral linker whereas the sense of enantioselection is determined by the configuration of these stereocentres. These stereodynamic diphosphinites induce higher enantioselectivities than the analogous stereodynamic diphosphanes derived from 2,2-biphosphole.

Diphosphine sulfides derived from 2,2'-biphosphole: novel chiral S,S ligands for palladium-catalyzed asymmetric allylic substitution.

Diphosphine sulfides derived from 2,2'-biphosphole have been efficiently synthesized in an enantiomerically pure form by a four step synthetic sequence. These S,S-ligands were used for the first time in Pd-catalyzed asymmetric allylic alkylation. Good yields and enantiomeric excess up to 73% were obtained.

Three new enantiomerically pure ferrocenylphosphole compounds.

The absolute configurations of three new enantiomerically pure ferrocenylphosphole compounds, namely (2S,4S,S(Fc))-4-methoxymethyl-2-[2-(9-thioxo-9lambda5-phosphafluoren-9-yl)ferrocenyl]-1,3-dioxane, [Fe(C5H5)(C23H22O3PS)], (III), (S(Fc))-[2-(9-thioxo-9lambda5-phosphafluoren-9-yl)ferrocenyl]methanol, [Fe(C5H5)(C18H14OPS)], (V), and (S(Fc))-diphenyl[2-(9-thioxo-9lambda5-phosphafluoren-9-yl]ferrocenylmethyl]phosphine, [Fe(C5H5)(C30H23P2)], (VIII), have been unambiguously established. All three ligands contain a planar chiral ferrocene group, bearing a dibenzophosphole and either a dioxane, a methanol or a diphenylphosphinomethane group on the same cyclopentadienyl. In compound (V), the occurrence of O-H...S and C-H...S hydrogen bonds results in the formation of a two-dimensional network parallel to (001). The geometry of the ferrocene frameworks agrees with related reported structures.