PENTACOORDINATE SPIROCYCLIC DERIVATIVES OF THE 2H-1,2,3-DIAZAPHOSPHOLE SYSTEM

Abstract

Stable spirocyclic phosphoranes 2 have been prepared stereospecifically in high yields (90–95%) by reaction of o-azidophenol with cis and trans-diazaphosphole derivatives 1. Slow isomerization of pure diastereoisomer 2 was observed in acidic conditions.     

A PROTON NMR STUDY OF THE STEREOCHEMISTRY AND KINETICS OF THE REACTIONS OF DIMETHYL SULFOXIDE WITH POTASSIUM DICLOROGLYCINATOPLATINATE(II) AND ITS METHYL DERIVATIVES

Abstract

Amino acid complexes of general formula K[Pt(NO)Cl₂], where NO denotes the metal bonded atoms of the amino acid, react completely with solvent DMSO to yield two products, cis- and trans-Pt(NO) (DMSO)Cl, where cis and trans refer to positions of DMSO relative to coordinated nitrogen. The products were identified and kinetic data were obtained from changes in the proton nmr spectra of the amino acid, when DMSO-d₆ was the solvent, or of both amino acid and coordinated DMSO, when ordinary DMSO was the solvent. For glycine and π-aminoisobutyric acid complexes, the rate of displacement of trans chloride exceeds that of cis chloride by a factor of 3. However, subsequent equilibration favors the cis isomer over the trans isomer by a factor of 10. By contrast, for the corresponding N, N-dimethyl derivatives, the rates of formation of the two isomers are more nearly the same and the equilibrium ratio does not differ from the kinetic ratio. In addition to providing a sensitive technique for evaluating small differences in kinetic trans-effects, these observations strongly suggest that the stereochemistry of Pt(NO) (DMSO)Cl for the corresponding alanine complex described by Kukushkin and Guryamava should be denoted cis, rather than the trans reported.     

ASYMMETRIC SYNTHESIS OF PROLINE USING COBALT(III)-TETRAAMINE COMPLEXES

Abstract

The decarboxylation reaction of δ -cis-β-[Co(L₁)(pdH)]²⁺ complex yielded δ -cis-β-[Co(L₁) (R-pro)]²⁺, while the δ -cis-β-[Co(L₂) (S-pro)]²⁺ was obtained from the reaction of δ -cis-β-[Co(L₂) (pdH)]²⁺, where L₁ is (3R)3-methyl-1, 6-bis[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, L₂ is (3S) 3-methyl-1, 6-bis-[(2S)-pyrrolidin-2-yl]-2, 5-diazahexane, and pdH is the pyrrolidine-2, 2-dicarboxylate ion. The asymmetrically synthesized prolines were isolated via the decomposition of the decarboxylated complexes. The proline isolated from δ -cis-β-[Co(L₁) (R-pro)]²⁺ showed a specific rotation of +12.0, representing a 24% excess of R-proline over S-proline, while the proline isolated from δ -cis-β-[Co(L₂) (S-pro)]²⁺ showed a specific rotation of -10.0, indicating a 20% excess of S-proline over R-proline.     

ON THE REARRANGEMENT OF N-ARYL SULFIMIDES

Abstract

N-Aryl-S,S-dialkylsulfimides, 1, with R¹ = alkyl other than CH₃, have been rearranged by heating in ethanol yielding o-alkylthiomethyl-anilines, 2, as main products. Isomeric o-methylthioalkyl-anilines, 14, are formed in minor amounts only. Reactions of sulfimides, 1, with R¹ = CH₃, with certain alkylating or acylating agents yielded o-methylthiomethylated, N-alkylated or -acylated products 9. Mechanistic considerations are discussed. The rearrangement of sulfimides 1 has been assumed to occur via [2,3]-sigmatropic reactions of intermediate azasulfonium ylids 3. Attempts to resolve (+)-camphor-10-sulfonates of N-aryl sulfimides failed, but optically active N-aryl sulfimides could be obtained by reaction of anilines with optically active sulfoxides and P₄O₁₀. Optically active 2,6-disubstituted sulfimides, 1, could be rearranged in ethanolic KOH to yield optically active cyclohexadienimines 12, indicating a transfer of asymmetry from sulfur to carbon and supporting the assumption of a sigmatropic rearrangement.     

3-D frameworks assembled by lanthanide dimers with 1,4-cyclohexanedicarboxylic acid and 1,10-phenanthroline via hydrogen bonds and π–π stacking interactions

Two complexes [Ln(e,a-cis-1,4-chdc)(e,a-cis-1,4-Hchdc)(phen)(H₂O)]₂?10H₂O (Ln = Eu, 1; Tb, 2, 1,4-H₂chdc = 1,4-cyclohexanedicarboxylic acid; phen = 1,10-phenanthroline) have been synthesized and structurally characterized by single-crystal X-ray diffraction. Both complexes are doubly e,a-cis-1,4-chdc-bridged dimers. The e,a-cis-1,4-Hchdc, phen, and water molecules bond to Ln³⁺, forming nine-coordinate complexes. 3-D supramolecular frameworks are constructed by hydrogen bonds and π–π stacking interactions. Luminescence spectra exhibit the ⁵D₀ → ⁷F _J (J = 0–4) and ⁵D₄ → ⁷F _J (J = 6–3) transitions of Eu³⁺ for 1 and Tb³⁺ ion for 2, respectively.     

Crystal structures and thermal decomposition oftrans-Pd(Creat)2Cl2·2H2O andcis-Pt(Creat)2I2·3H2O

New complexes of the formulaetrans-Pd(Creat)₂Cl₂·2H₂O (I) andcis-Pt(Creat)₂I₂·3H₂O (II) have been prepared and their structures and stabilities studied by X-ray diffraction and thermal analysis. Both compounds have a squareplanar geometry, the two Cl atoms and N1 creatinine atoms are coordinated to Pd intrans configuration, while in compoundII the I atoms and N1 atoms are coordinated incis configuration. In spite of the earlier differences, the TG and DTA curves of the complexes show that their stability is very similar. Since an extended hydrogen bond system is present in the crystals, especially inII, the possible consequences in biological media are discussed briefly.

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Kristallstrukturen und thermische Zersetzung vontrans-Pd(Creat)₂Cl₂·2H₂O undcis-Pt(Creat)₂I₂·3H₂O

Zusammenfassung Es wurden neue Komplexe der Formelntrans-Pd(Creat)₂Cl₂·2H₂O (I) undcis-Pt(Creat)₂I₂·3H₂O (II) hergestellt und ihre Strukturen und Stabilitäten mittels Röntgenstrukturanalyse bzw, thermischer Analyse untersucht. Beide Komplexe haben quadratisch-planare Struktur, die zwei Cl-Atome und die N1-Creatinin-Atome sind an Pd intrans-Konfiguration koordiniert, währenddessen in VerbindungII die I-Atome und die N1-Atome incis-Konfiguration zueinander stehen. Trotz früherer Differenzen zeigen die TG- und DTA-Kurven der Komplexe, daß ihre Stabilitäten sehr ähnlich sind. Da besonders inII ein ausgedehntes Wasserstoffbindungssystem vorhanden ist, werden auch mögliche Konsequenzen bezüglich biologischer Wirksamkeit kurz diskutiert.

     

Cu(II)/Cd(II) coordination polymers based on polycarboxylate and 2-(2-pyridyl)benzimidazole

Three polycarboxylate coordination polymers containing 2-(2-pyridyl)benzimidazole as co-ligand, [Cu(Bdc)(2-PyBIm)] _n (1), [Cu(HBtc)(2-PyBIm)] _n (2) and [Cd₂(HBtc)₂(2-PyBIm)₂] _n ·; nH₂O (3) (H₂Bdc?=?1,4-benzenedicarboxylic acid; H₃Btc?=?1,3,5-benzenetricarboxylic acid), have been synthesized and characterized by elemental analyses, IR spectra, TG-DSC and X-ray structural analyses. Complex 1 is a one-dimensional zigzag chain in which the Cu(II) is cis six-coordinated by two chelating carboxyl groups and a 2-PyBIm ligand. Complex 2 is a two-dimensional (4, 4) network in which H₃Btc is partially deprotonated. Complex 3 has a three-dimensional framework in which one Cd(II) is six-coordinate and the other is seven-coordinate. All 2-PyBIm groups are neutral, chelating, bidentate ligands in 1–3. These complexes are quite thermally stable. The luminescence of 3 has also been investigated.     

SYNTHESIS AND CONFIGURATIONAL STUDIES OF ARYL CYCLOPROPYL SULFONES

Abstract

The cycloaddition of arylthiocarbenes to styrene gave stereospecifically cis?1-(arylthio)-2-phenylcyclopropanes, which were subsequently oxidized to the corresponding sulfones. The cyclopropanation of α,β-unsaturated sulfones with dimethylsulfonium methylide yielded stereoselectively trans?1-(arylsulfonyl)-2-arylcyclopropanes. The configurational assignments of these compounds have been arrived at on the basis of IR and PMR spectral data. Chemical shifts for ring protons and other substituents reveal that all the substituents tend to cause protons cis to them to appear at higher fields than those trans to them. This has been used as a criterion to distinguish between cis and trans aryl cyclopropyl sulfones.     

STEREOCHEMICAL PROPERTIES OF THE 1-CHLORO-1- PHENYL-2,5-DIMETHYL-2-PHOSPHOLENIUM ION AND DERIVED OXIDE AND PHOSPHINE

Abstract

The cycloaddition of phenylphosphonous dichloride and trans, trans-2,4-hexadiene, or the addition of chlorine to trans-1-phenyl-cis-2,5-dimethyl-3-phospholene, gave 1-chloro-1-phenyl-2,5-dimethyl-2-phospholenium chloride. This compound shows no evidence in its ³¹P and ¹H nmr spectra for the existence of cis, trans isomers, yet on hydrolysis or dehalogenation with magnesium the resulting oxide and phosphine, respectively, are seen to be isomer mixtures. This phenomenon is explained by a rapid equilibration of the cis, trans form of the I-chloro ion through a pentacovalent species. Structures of the oxides and phosphines were assigned by ¹H and ¹³C nmr relations. The 1-phenyl-cis-2,5-dimethyl-3-phospholenium ion and related compounds were also characterized.     

CHARACTERIZATION OF CIS- AND TRANS-DINITROBIS-(l-CYCLOHEXANEDIAMINE)-COBALT(III) CHLORIDE1

Abstract

Two geometrical isomers of [Co(l-chxn)₂(No₂)₂]Cl have been isolated. The trans-isomer is eluted first from a cellulose ion exchange column as a single isomer. The cis-isomer corresponds to the complex previously reported as the trans-isomer. The cis-isomer with the same CD sign pattern as for the trans-isomer is stereoselectively favored, but a small amount of the second cis-isomer separates using Cellex CM ion exchange cellulose. The CD spectra of the cis- and trans- isomers are similar to those of the corresponding isomers of the l-pn complex.     

SYNTHESIS AND CHARACTERIZATION OF A SERIES OF LIPOPHILIC CISPLATIN ANALOGS WITH CIS-1,4-DIAMINOCYCLOHEXANE AS NONLEAVING AMINE LIGAND

Abstract

A series of lipophilic platinum(II) complexes of the type [Pt(cis-1,4-DACH)L₂] (where cis-1,4-DACH = cis-1,4-diaminocyclohexane and L = acetate, propionate, butyrate, valerate, hexanoate, heptanoate, octanoate, 2,2′-dimethyloctanoate, nonanoate, decanoate, undecanoate, laureate, tridecanoate, myristate, pentadecanoate, palmitate, heptadecanoate, stearate, nonadecanoate, or eicosanoate) has been synthesized and characterized by elemental analysis and by infrared, ¹³C, and ¹⁹⁵Pt nuclear magnetic resonance spectroscopic techniques.     

REACTIONS OF TELLURIUM TETRAHALIDES WITH GLYCOLS

Abstract

Tellurium tetrahalides undergo reaction with glycols to yield three different products: O,O'-dioxotrihalotellurates; bis(alkoxy)dihalotellurium (IV) compounds and hexahalotellurates. The course of the reaction appears to be determined primarily by the nature of the glycol. The structure of dichlorobis(cis- 2-hydroxycyclohexyloxy)tellurium(IV) has been determined crystallographically     

THE SYNTHESIS OF GEM-CYCLOPENTYL SUBSTITUTED GLUTARATES VIA THE OXIDATIVE RING CONTRACTION OF 2-ACETYLCYCLOHEXANONES

ABSTRACT

A two step synthesis of differentially protected gem-cyclopentyl glutarates has been developed from 2-acetylcyclohexanone and acrylates. The key step involves an oxidative ring contraction reaction with hydrogen peroxide. The methodology has been used to prepare intermediates used in the preparation of the atriopeptidase inhibitor candoxatril.     

Hybrid-DFT Study and NBO Interpretation of the Configurational Behavior of 2-Halotetrahydrothiopyran S-Oxides

Abstract

Natural bond orbital (NBO) interpretation and hybrid density functional theory (hybrid-DFT: B3LYP/Def2-TZVPP)-based methods were used to investigate the impacts of the generalized anomeric effects (GAE), electrostatic, and steric interactions on the conformational properties of cis and trans isomers of 2-fluoro-, 2-chloro-, and 2-bromotetrahydrothiopyran S-oxide (1–3). The results obtained showed that the trans-axial configurations are the most stable forms of compounds 1–3. Based on the results obtained, the instability of the second lowest energy-minimum (cis-equatorial configuration, with axial S?O and equatorial C?X bonds, X = halogen atoms) increases from compound 1 to compound 3. This trend is also observed for the third lowest energy-minimum (i.e., the trans-equatorial configuration). Contrary to the trend observed for the cis- and trans-equatorial forms, the instability of the cis-axial form compared to the trans-axial form, increases from 1 to 2 but decreases slightly from 2 to 3. The correlations between the GAE, bond orders, steric effects, ΔG, Δμ, structural parameters, and conformational and configurational behaviors of compounds 1–3 have been investigated.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Interaction of 2-aminopyrimidine with dichloro-[1-alkyl-2-(naphthylazo) imidazole]palladium(II) complexes : Kinetic and mechanistic studies

Background  

The anticancer properties of cisplatin and palladium(II) complexes stem from the ability of the cis-MCl₂ fragment to bind to DNA bases. However, cisplatin also interacts with non-cancer cells, mainly through bonding molecules containing -SH groups, resulting in nephrotoxicity. This has aroused interest in the design of palladium(II) complexes of improved activity and lower toxicity. The reaction of DNA bases with palladium(II) complexes with chelating N,N^/donors of the cis-MCl₂ configuration constitutes a model system that may help explore the mechanism of cisplatin's anticancer activity. Heterocyclic compounds are found widely in nature and are essential to many biochemical processes. Amongst these naturally occurring compounds, the most thoroughly studied is that of pyrimidine. This was one of the factors that encouraged this study into the kinetics and mechanism of the interaction of 2-aminopyrimidine (2-NH₂-Pym) with dichloro-{1-alkyl-2-(α-naphthylazo)imidazole}palladium(II) [Pd(α-NaiR)Cl₂, 1] and dichloro-{1-alkyl-2-(β-naphthylazo)imidazole}palladium(II) [Pd(β-NaiR)Cl₂, 2] complexes where the alkyl R = Me (a), Et (b), or Bz (c).     

THE CRYSTAL AND MOLECULAR STRUCTURE OF PRASEODYMIUM(III) 2-FURANCARBOXYLATE DIHYDRATE

Abstract

Praseodymium(III) 2-furanocarboxylate dihydrate is monoclinic, space group P2₁/c. The lattice parameters area a = 10.349(2). b = 16.727(3), c = 9.458(1) Å, β = 92.61(1)°. The crystal structure was solved and refined by a full-matrix least-squares method to R = 0.034 and R_w = 0.039 from 2333 reflections. Carboxylic ions bond in the complex as bidentates and as bi- and terdentate-bridging ligands. The water molecules bond to the metal. The coordination number of the praseodymium atom is nine. The coordination polyhedron is intermediate between a distorted tricapped trigonal prism and a distorted monocapped square antiprism.     

A Closer Look at the Hydroiodination of Propiolic Acid

The crystal structures of cis‐3‐iodoacrylic acid (1), trans‐3‐iodoacrylic acid (2), trans‐3‐iodoacrylic acid methyl ester (3), 3,3‐diiodopropanoic acid (4), and trans‐2,3‐diiodoacrylic acid (5) are reported. Compounds 1 and 2 are the kinetic and thermodynamic products, respectively, of the hydroiodination of propiolic acid. Compound 4 results from addition of a second equivalent of hydroiodic acid to 1 or 2, whereas 5 results from the addition of trace elemental iodine to propiolic acid.     

THE SYNTHESIS OF FLUOROHETEROCYCLIC KETENE AMINALS

The synthesis of fluoroheterocyclic ketene aminals was investigated. Fluorobenzyl ketene dithioacetals 1c reacted with nitric acid in the presence of concentrated sulfuric acid to give compound 2c. 1 reacted with diamines to afford 3–4. C-fluorobenzylation of 3–4 give the corresponding 5–8.     

PLATINUM(II) COMPLEXES OF P(III) CYCLOPHOSPHAMIDE DERIVATIVES

Abstract

The syntheses of the P(III) analogues of cyclophosphamide, isophosphamide and triphosphamide are reported. These compounds (4–6, respectively) polymerize easily at room temperature but are sufficiently stable in solution to react with Cl₂Pt(NCPh)₂, forming cis-Cl₂Pt(4)₂, cis-Cl₂Pt(5)₂ and cis-Cl₂Pt(6)₂ (complexes 9–11, respectively). Complex 10 can also be made by condensing cis-Cl₂Pt[ClPN(CH₂CH₂Cl)CH₂CH₂CHO]₂ with ClCH₂CH₂NH₂, while an alternate route to 9 and 11 is afforded by the condensation of cis-Cl₂Pt[Cl₂PN(CH₂CH₂Cl)₂]₂ with H₂NCH₂CH₂CH₂OH and ClCH₂CH₂NHCH₂CH₂CH₂OH, respectively. Complexes 9–11 exist in two diastereomeric configurations and these can be separated in the cases of 9 and 11 by column chromatography. ³¹P NMR spectral data for the complexes are discussed and the results of NCl antitumor screening are presented.     

A Study of the Effect of Catalyst on Stereochemistry in the Hydrogenation of N-(Menthyloxycarbonyl)-N-Methyl-2-(N-Pyrrolidinyl)-1-cyclohexenamine

Catalytic hydrogenation of N-(menthyloxycarbonyl)-N-methyl-2-(1-pyrrolidinyl)-1-cyclohexenamine (3) gave mainly 1R,2S-cis-N-(menthyloxycarbonyl)- and 1S,2R-cis-N-(menthyloxycarbonyl)-N-methyl-2-(1-pyrrolidinyl)cyclohexylamines 7 and 8 with diastereoselectivity favoring the 1S,2R-isomer 8.