Unexpected Formation of a Chiral spiro-system in the Reaction of the Dilithium Derivative of Hexafluorocumyl Alcohol with N-(t-butylsulfenyl)phthalimide.

An unexpected course of the reaction of hexafluorocumyl alcohol dilithium derivative 2 with N-(t-butylsulfenyl)phthalimide (3) has been presented. The process proceeded under mild conditions and resulted in previously undescribed chiral spiro-system- 3',3'-bis(trifluoromethyl)-3H,3'H-1,1'-spirobis(isobenzofuran)-3-one (5) as the only product. A detailed spectral analysis of the product has been provided, and mechanistic aspects have been investigated.

New Optically Active -Butylarylthiophosphinic Acids and Their Selenium Analogues as the Potential Synthons of Supramolecular Organometallic Complexes: Syntheses and Crystallographic Structure Determination.

The aim of the research described in this publication is two-fold. The first is a detailed description of the synthesis of a series of compounds containing a stereogenic heteroatom, namely the optically active -stereogenic derivatives of -butylarylphoshinic acids bearing sulfur or selenium. The second is a detailed discussion dedicated to the determination of their structures by an X-ray analysis.

Nucleophilic Substitution at Tricoordinate Sulfur-Alkaline Hydrolysis of Optically Active Dialkoxysulfonium Salts: Stereochemistry, Mechanism and Reaction Energetics.

Optically active dialkoxyisopropylsulfonium salts were obtained by methylation (ethylation) of optically active alkyl isopropanesulfinates using methyl (ethyl) trifluoromethanesulfonate. Alkaline hydrolysis of a series of methoxy(alkoxy)sulfonium salts afforded the two sulfinate products methyl isopropanesulfinate and alkyl isopropanesulfinate, both formed with a slightly prevailing inversion of configuration at the sulfur atom. DFT calculations revealed that this substitution reaction proceeded stepwise according to an addition-elimination (A-E) mechanism involving the formation of high tetracoordinate S sulfurane intermediates.

Microbiologically Pure Cotton Fabrics Treated with Tetrabutylammonium OXONE as Mild Disinfection Agent.

The microbiological purity of textiles plays a pivotal role in the use of textiles, especially in hospitals and other medical facilities. Microbiological purity of cotton fabric was achieved by a new disinfection method using tetrabutyloammonium OXONE (TBA-OXONE) before washing. As a result of the disinfection, the cotton fabric became microbiologically pure, despite the markedly decreased washing time with respect to the widely used standard procedure.

New Insights into Green Protocols for Oxidative Depolymerization of Lignin and Lignin Model Compounds.

Oxidative depolymerization of lignin is a hot topic in the field of biomass valorization. The most recent and green procedures have been herein detailed. Photochemical and electrochemical approaches are reviewed highlighting the pros and cons of each method.

Chiral Polythiophenes: Part I: Syntheses of Monomeric Precursors.

The purpose of this mini-review is to comprehensively present the synthetic approaches used for the preparation of non-racemic mono- and multi-substituted thiophenes, which, in turn, can be applied as precursors for the synthesis of chiral polythiophenes isolated as a single chemical entity or having supramolecular thin-layer architectures.

Absolute Configuration and Conformation of (-)---Butylphenylphosphinoamidate: Chiroptical Spectroscopy and X-ray Analysis.

The absolute configuration and conformations of (-)--butylphenylphosphinoamidate were determined using three different chiroptical spectroscopic methods, namely vibrational circular dichroism (VCD), electronic circular dichroism (ECD), and optical rotatory dispersion (ORD). In each of the spectroscopic methods used, experimental data for the (-)-enantiomer of -butylphenylphosphinoamidate were measured in the solution phase. Using the concentration-dependent experimental infrared spectra, the existence of dimers in the solution was investigated, and the monomer-dimer equilibrium constant was determined.

The Chiral 1:2 Adduct ()()(-)-Ethyl 2-Phenylbutyl Sulphide-Mercury (II) Chloride:(-)[()()-Et(2-PhBu)S.(HgCl)]. Stereoselective Synthesis, Asymmetric Oxidation, Crystal and Molecular Structure and Circular Dichroism Spectra.

Optically active (-)ethyl ()-2-phenylbutyl thioether, (-)()-Et(PhBu)S (), and its new diastereoisomeric mercury (II) chloride adduct, 1:2, (-)[()()-Et(PhBu)S.(HgCl)], () were stereoselectively synthesized; the absorbance (UV) and circular dichroism (CD) spectra were measured and the crystal and molecular structure of complex () was determined by single-crystal X-ray diffraction. Two different Hg centres are present whose coordination environments are built by two short bonds to chloride ligands in one case, and to one chloride and one sulphur in the other one.

Diastereoisomerically Pure, ()--1,2--isopropyli dene-(5--α-d-glucofuranosyl) -butanesulfinate: Synthesis, Crystal Structure, Absolute Configuration and Reactivity.

The reaction of -butylmagnesium chlorides with diastereomerically pure ()-1,2--isopropylidene-3,5--sulfinyl-α-d-glucofuranose ()- was found to be stopped at the stage of the corresponding, diastereoisomerically pure 1,2--isopropylidene-(5--α-d-glucofuranosyl) -butanesulfinate ()- for which the crystal structure and the ()-absolute configuration was determined by X-ray crystallography. Comparison of the absolute configurations of the starting sulfite ()-, and -butanesulfinate ()- (which crystallizes in the orthorhombic system, space group P222, with the single compound molecule present in the asymmetric unit), clearly indicates that the reaction of nucleophilic substitution at the stereogenic sulfur atom in the sulfite ()- occurs with the full inversion of configuration via the trigonal bipyramidal sulfurane intermediate in which both the entering and leaving groups are located in apical positions.

Selenonium Ylides: Syntheses, Structural Aspects, and Synthetic Applications.

The goals of this mini review constitute a) a presentation of the synthetic protocols applied to the preparation of achiral and non-racemic selenonium ylides; b) discussion of their basic structural features, including their optical activity; and c) a description of their synthetic applications in general synthetic methodology and in asymmetric synthesis.

Diselenides and Benzisoselenazolones as Antiproliferative Agents and Glutathione-S-Transferase Inhibitors.

A series of variously functionalized selenium-containing compounds were purposely synthesized and evaluated against a panel of cancer cell lines. Most of the compounds showed an interesting cytotoxicity profile with compound showing a potent activity on MCF7 cells. The ethyl amino derivative acts synergistically with -platin and inhibits the GST enzyme with a potency that well correlates with the cytotoxicity observed in MCF7 cells.

Solvent-Free Michaelis-Arbuzov Rearrangement under Flow Conditions.

The first solvent- and catalyst-free procedure for the Michaelis-Arbuzov reaction under flow conditions was developed. A variety of alkylphosphonic esters could be obtained using this protocol starting from the corresponding trialkyl phosphites and even catalytic amounts of alkyl halides with very short reaction times (8.33-50 min) and excellent conversions.

1-(Acylamino)alkylphosphonic Acids-Alkaline Deacylation.

The alkaline deacylation of a representative series of 1-(acylamino)alkylphosphonic acids [(AC)-AA: (AC) = Ac, TFA, Bz; AA = Gly, Ala, Val, Pgl and Phe] in an aqueous solution of KOH (2M) was investigated. The results suggested a two-stage reaction mechanism with a quick interaction of the hydroxyl ion on the carbonyl function of the amide R-C(O)-N(H)- group in the first stage, which leads to instant formation of the intermediary acyl-hydroxyl adducts of R-C(O)₂-N(H)-, visible in the P NMR spectra. In the second stage, these intermediates decompose slowly by splitting of the RC(O)₂-N(H)- function with the subsequent formation of 1-aminoalkylphosphonate and carboxylate ions.

High-performance liquid chromatographic enantioseparation of N-aryl-thioureidoalkylphosphonates and thiourylenedi(alkylphosphonates) on polysaccharide-based chiral stationary phases.

The first successful enantioseparation of representative O,O-diphenyl-N-arylthioureidoalkylphosphonates, (±)-Ptc-Val (OPh) & (±)-Ptc-Leu (OPh) and thiourylenedi(isobutyl phosphonate), Tcm[Val (OPh) ] on analytical and semipreparative scale was achieved by high-performance liquid chromatography using polysaccharide-based chiral stationary phases (CPs). Atc-AA (OPh) was obtained using modified tricomponent condensations of the corresponding aldehydes, N-arylthiourea and triphenyl phosphite whereas Tcm[Val (OPh) ] by the condensations of aldehydes, thiourea, and triphenyl phosphite. The prepared, racemic (±)-Atc-AA (OPh) [(±)-Ptc-Val (OPh) , (±)-Ptc-Leu (OPh) , (±)-Ptc-Pgly (OPh) and (±)-Ntc-Pgly (OPh) ] and racemic (±)-Tcm[AA (OPh) ] [(±)-Tcm[Nva (OPh) ] & (±)-Tcm[Val (OPh) ] ] were adequately characterized and used for chromatographic separations on high-performance liquid chromatography-chiral stationary phases.

Chiral sulfoxides: advances in asymmetric synthesis and problems with the accurate determination of the stereochemical outcome.

Chiral sulfoxides are in extremely high demand in nearly every sector of the chemical industry concerned with the design and development of new synthetic reagents, drugs, and functional materials. The primary objective of this review is to update readers on the latest developments from the past five years (2011-2016) in the preparation of optically active sulfoxides. Methodologies covered include catalytic asymmetric sulfoxidation using either chemical, enzymatic, or hybrid biocatalytic means; kinetic resolution involving oxidation to sulfones, reduction to sulfides, modification of side chains, and imidation to sulfoximines; as well as various other methods including nucleophilic displacement at the sulfur atom for the desymmetrization of achiral sulfoxides, enantioselective recognition and separation based on either metal-organic frameworks (MOF's) or host-guest chemistry, and the Horner-Wadsworth-Emmons reaction.

Chiral Hypervalent, Pentacoordinated Phosphoranes.

This review presents synthetic procedures applied to the preparation of chiral (mainly optically active) pentacoordinated, hypervalent mono and bicyclic phosphoranes. The mechanisms of their stereoisomerization and their selected interconversions are also presented.

Self-disproportionation of enantiomers via achiral gravity-driven column chromatography: A case study of N-acyl-α-phenylethylamines.

Herein we report a study of the self-disproportionation of enantiomers (SDE) via gravity-driven achiral column chromatography of a series of amides derived from 1-phenylethylamine. We demonstrated that structural and electronic factors of the substituents play an important role in the observed magnitude of the SDE. For the first time, the SDE phenomenon of amides with that of thioamides was compared.

Remarkable magnitude of the self-disproportionation of enantiomers (SDE) via achiral chromatography: application to the practical-scale enantiopurification of β-amino acid esters.

We report the best performance yet for the self-disproportionation of enantiomers (SDE) via achiral chromatography as typically used in laboratories for the isolated yield of the excess enantiomer using N-acetyl β-amino acid ethyl esters. The results are the most convincing ever demonstration of the capability of the SDE for practical-scale enantiopurification as comparable, or even superior for some systems, to that of recrystallization. For example, from a sample of 94.

Reactivity of aminophosphonic acids. Oxidative dephosphonylation of 1-aminoalkylphosphonic acids by aqueous halogens.

The reactions of 1-aminoalkylphosphonic acids with bromine-water, chlorine-water and iodine-water were investigated. The formation of phosphoric(v) acid, as a result of a halogen-promoted cleavage of the Cα-P bond, accompanied by nitrogen release, was observed. The dephosphonylation of 1-aminoalkylphosphonic acids was found to occur quantitatively.

The nomenclature of 1-aminoalkylphosphonic acids and derivatives: evolution of the code system.

The approach for the unification of published proposals for the nomenclature and abbreviations of aminoalkylphosphonic acids and their derivatives is presented. Their modification was made on the basis of the IUPAC-IUB rules concerning the nomenclature and code system of proteinogenic amino acids. Our present proposal formulates the supplementary code and nomenclature system allowing unambiguous description of phosphonic analogs of proteinogenic amino acids, their analogs, homologs, metabolites, and derivatives including phosphonopeptides.

Acid catalyzed alcoholysis of sulfinamides: unusual stereochemistry, kinetics and a question of mechanism involving sulfurane intermediates and their pseudorotation.

The synthesis of optically active sulfinic acid esters has been accomplished by the acid catalyzed alcoholysis of optically active sulfinamides. Sulfinates are formed in this reaction with a full or predominant inversion of configuration at chiral sulfur or with predominant retention of configuration. The steric course of the reaction depends mainly on the size of the dialkylamido group in the sulfinamides and of the alcohols used as nucleophilic reagents.

The self-disproportionation of the enantiomers (SDE) of methyl n-pentyl sulfoxide via achiral, gravity-driven column chromatography: a case study.

This work explores the self-disproportionation of enantiomers (SDE) of chiral sulfoxides via achiral, gravity-driven column chromatography using methyl n-pentyl sulfoxide as a case study. A major finding of this work is the remarkable persistence and high magnitude of the SDE for the analyte. Thus, it is the first case where SDE is observed even in the presence of MeOH in the mobile phase.

Anticancer evaluation of some newly synthesized N-nicotinonitrile derivative.

Some novel N-nicotinonitrile derivatives 3-14 have been synthesized starting with compound 1. The key step of this work is the coupling between compound 1 and activated sugars to afford the corresponding cyclic nucleosides 3-6. Moreover, the cytotoxicity and in vitro anticancer evaluation of the prepared compounds have also been assessed against breast MCF-7 cancer, liver HepG2 cancer and lung A549 carcinoma cell lines with investigation the effect of the synthesized compounds on the expression of urokinase plasminogen activator (uPA).

One-pot tandem 1,4-1,2-addition of phosphites to quinolines.

Trialkyl and silylated dialkyl phosphites were evaluated as phosphorus nucleophiles for the addition to quinolines in a strong acidic medium allowing consecutive 1,4- and 1,2-addition breaking up the aromatic stabilisation, thereby leading to 2,4-diphosphono-1,2,3,4-tetrahydroquinolines in one single reaction step in moderate to good yields (2-84%).

Diastereomers of N-alpha-phenylethyl-t-butylsulfinamide: absolute configurations and predominant conformations.

N-alpha-Phenylethyl-t-butylsulfinamide is a complicated system for determining molecular stereochemistry because of numerous possibilities for assigning the absolute configuration and a predominant conformation. Two diastereomers of N-alpha-phenylethyl-t-butylsulfinamide derived from (-)-(S)-alpha-phenylethyl amine, a (+)-diastereomer and a (-)-diastereomer, have been synthesized and their experimental chiroptical spectroscopic properties have been measured. These properties include vibrational circular dichroism, electronic circular dichroism and optical rotatory dispersion.