Synthesis of (−)-Dihydroraputindole D by Enantioselective Benzoylation of a 1,3-Diol Intermediate

The enantioselective synthesis of (−)-dihydroraputindole D is reported. The key step is the desymmetrizing benzoylation of a prochiral 1,3-diol employing Trost′s ProPhenol catalyst system, which has been applied for the first time to a cyclic molecule carrying geminal hydroxymethyl groups. The cyclopenta[f]indoline system was assembled by Au(I)-catalyzed cyclization of an alkynylated indoline precursor. (−)-Dihydroraputindole D was obtained in 17 steps and 8% overall yield starting from dihydroxyacetone. In combination with quantum chemical calculations of the ECD spectra, our synthesis allowed us to determine the absolute configuration (5S,7R) of the natural product (+)-raputindole D from the Rutaceous plant Raputia simulans.     

Unexpected formation of a chiral δ-lactone by reduction of the 1,3-dicarbonylic cyclopentanoid derivatives

We have described the synthesis of highly functionalized chiral cyclopentanoids, which are important building units for synthesis of biological active compounds. The (−)- or (+)-7,7-dimethoxy-1,4,5,6-tetrachlorobicyclo[2.2.1]hept-5-en-2-endo-yl acetate, obtained from the enzyme catalyzed transesterification of the racemate, was converted to α-diketone chiral. The α-diketone was treated with H₂O₂/NaOH and esterified with CH₂N₂ to furnish a mixture of the compounds (+)- or (−)-10 and (+)- or (−)-11. The reduction of the (+)- or (−)-10 and/or (+)- or (−)-11 with BH₃·THF furnished the lactone (+)- or (−)-13 with excellent yield. The α-diketone was reduced with indium metal in the presence of NH₄Cl furnishing the acyloin (+)-14 in 67% of yield. The treatment of acyloin (+)-14 with Pb(OAc)₄ furnished the aldehyde (+)-15 with 80% of yield. The reduction of the aldehyde (+)-15 with NaBH₄ has again produced the lactone (+)-13.     

Theoretical study on conformational conversion of 1,3-dioxane inside a capsular host

The conformational conversion of 1,3-dioxane guest encapsulated inside a cylindrical capsular host was investigated with PM3 method and single point energies were evaluated by B3LYP method. When entrapped in the capsule, the guest tumbles were slower than that in the free condition. The influences of the inner phase of the capsule on the guest conformational conversion were discussed in detail.     

Synthesis of 1,3-diphenyl-6-alkyl/aryl-substituted fulvene chromophores: observation of π-π interactions in a 6-pyrene-substituted 1,3-diphenylfulvene

The synthesis, structural, and electronic properties of nine 1,3-diphenyl-6-alkyl/aryl substituted pentafulvenes were studied. Pyrene ring π-π interactions were revealed from analysis of the experimental crystal packing of 1,3-diphenyl-6-(1-pyrene)fulvene and supporting DFT calculations. Photophysical properties derived from UV-vis and fluorescence emission measurements demonstrated tunable and low HOMO-LUMO band gaps for the series. The presented results point to a model synthetic approach for incorporation of extended π systems and donor-π-acceptor groups for fulvene-based electronic materials.     

Hydrochlorination of δ2-1,3-oxazolines and 1,3-oxazolidines

The compounds 2-(ethoxycarbonylmethyl)-²-l,3-oxazoline and 1-methyl-2-(methoxycarbonylmethylene)-1,3-oxazolidine are hydrochlorinated at the C=N or C= C bond, respectively, with subsequent opening of the oxazolidine ring. Depending on the reaction conditions, this occurs regioselectively to form various products.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 684–686, May, 1992     

Separation of diastereomers of a 1,3-disubstituted tetrahydro-β-carboline by capillary electrophoresis with β-cyclodextrin

Summary Capillary zone electrophoresis with -cyclodextrin as electrolyte additive has been investigated for the separation of the diastereomers of a 1,3-disubstituted tetrahydro--carboline. The effects of pH, buffer concentration, -cyclodextrin concentration and applied voltage on resolution were investigated. This study shows that optimizing the assay conditions leads to maximum chiral separation or resolution. The method enables further research on the quantitative analysis of these compounds.     

Reactions of enamines with fluorinated acyl chlorides----Synthesis of fluorinated 1,3-diketones and 1,3-keto-aldehydes

The reactions of enamines (1a-b,4,6) with fluorinated acyl chlorides (2a-d) produced fluorinated 1,3-diketones (3a-f) and 1,3-keto-aldehydes (7a-c) in good yields as well as byproducts fluorinated acylamides (5a-c).It is proposed that the reactions involve nucleophilic attack by the C-atora and/or N-atom of the enamines on acyl carbon of the fluorinated acyl chlorides.     

Natural effectors of β-1,3-glucanases activator of the β-1,3-glucanases of marine mollusks

The capacity of certain extracts of marine invertebrates of the Indian and Pacific Oceans for activating -1,3-glucanases has been detected. It has been shown that an individual compound — swinholide A from the spongeTheonella swinhoei — specifically activates -1,3-glucanases of bivlve mollusks. In the presence of swinholide A both the hydrolysis of laminarin by -1,3-glucanase L-IV fromSpisula sachalinensis and the transglycosylation reaction are accelerated.Pacific Ocean Institute of Bioorganic Chemistry, Far Eastern Branch, Russian Academy of Sciences, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, Nos. 3,4, pp. 316–320, May–August, 1992.     

Kinetic Studies of Electrochemical Oxidation of 1,3-Benzenedithiol

The electrochemical oxidation of 1, 3-benzenedithiol was investigated in a 0. 100 mol/L tetrabutylammonium perchlorate/acetonitrile electrolyte. The electrochemical techniques used were potential sweep, bulk electrolysis, rotating disc and the potential step method. The combination of the techniques yielded the number of electrons transferred per molecule, the reaction order, the transfer coefficient, the diffusion coefficient and concentration of dithiol anions, the standard heterogeneous rate constant as well as the formal potential and equilibrium constant of the preceeding dissociation reaction. This paper also illustrates the methods for studying the electrode kinetics of reactions which (a) involve a chemical reaction preceeding the electron-transfer process, (b) have insoluble polymer products, and (c) are totally irreversible.     

Functionalization of N2 via Formal 1,3-Haloboration of a Tungsten(0) σ-Dinitrogen Complex

Boron tribromide and aryldihaloboranes were found to undergo 1,3-haloboration across one W−N≡N moiety of a group 6 end-on dinitrogen complex (i.e. trans-[W(N₂)₂(dppe)₂]). The N-borylated products consist of a reduced diazenido unit sandwiched between a W^II center and a trivalent boron substituent (W−N=N−BXAr), and have all been fully characterized by NMR and IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Both the terminal N atom and boron center in the W−N=N−BXAr unit can be further derivatized using electrophiles and nucleophiles/Lewis bases, respectively. This mild reduction and functionalization of a weakly activated N₂ ligand with boron halides is unprecedented, and hints at the possibility of generating value-added nitrogen compounds directly from molecular dinitrogen.     

Synthesis of Some Potential Antiangiogenic 1,3-Dihydro-1,3-dioxo-2H-isoindole Derivatives

The proliferation, invasion and metastasis of malignant tumors are closely related withangiogenesis induced by tumor cells. Blocking tumor-induced angiogenesis is anefficient strategy to prevent and cure cancer1. Recent studies indicated that theangiogenic process depends on vascular endothelial cell migration and invasion, whichregulated by αvβ3 receptor2. The receptor and extracellular matrix can recognize eachother through Arg-Gly-Asp (RGD) consensus sequence found in matrix ligands…     

Synthesis and Insulin—sensitizing Activity of a Series of 2—Benzyl—1,3—dicarbonyl Derivatives

A series of 2-benzyl-1,3-dicabonyl derivatives was synthesized.Their insulin-sensitizing activity was evaluated in 3T3-L1 preadipocyte cells.Compounds3,26 and 27 were found to possess strong insulin-sensitizing activity in vitro and were selected for further hypoglycemic evaluation in vivo.     

Modular evolution of a chiral auxiliary for the 1,3-dipolar cycloaddition of isomünchnones with vinyl ethers

[reaction: see text]. The 1,3-dipolar cycloaddition reaction has long been recognized as a powerful methodology in organic synthesis. More recently, this reaction has become a popular manifold for the construction of chemical diversity. Herein, we report the development of a chiral template for the facially selective cycloaddition of isomünchnones, a common class of 1,3-dipoles. The modular format of the asymmetric unit allowed a systematic optimization of selectivity. In addition, the chiral auxiliary was removed through an unusually facile ester aminolysis.     

Hyperbranched modification of unsaturated side chains of polyethylene introduced by γ-ray irradiation under a 1,3-butadiene atmosphere

 Amino and other functional groups were introduced to a polyethylene substrate starting from the unsaturated pendant and bridge groups (collectively called side chains) of polyethylene, which had been prepared by γ-ray irradiation under an atmosphere of 1,3-butadiene of the polyethylene substrate (the drawn film of ultra-high- molecular-weight polyethylene, Mˉv: 5 × 10⁶). 2-Aminoethylamino groups were introduced to the side chains through treatment either with bromine or with peracetic acid vapor followed by immersion in ethylenediamine. Introduction of amino groups were confirmed by Fourier transform IR spectrometry, ninhydrin test, and acid–base titration. Starting from 2-aminoethylaminated polyethylene, modification cycles to grow a dendrimer on the film were applied; these consisted of 2-methoxycarbonylethylation and 2-aminoethylamidation. This technique resulted in hyperbranched modification of the polymer. The product is a kind of dendrimer grown on the surface of polyethylene film with amplified amino ends and has anion-exchange capacity and absorbs acid dye. Its application in practical uses is discussed. Received: 31 March 2000 Accepted: 2 January 2001     

Diversity-oriented one-pot multicomponent synthesis of chromanone-based 3,3′-pyrrolidinyl-spirooxindoles via a 1,3-dipolar cycloaddition reaction

A new methodology was developed for the highly efficient one-pot multicomponent synthesis of chromanone-based 3,3′-pyrrolidinyl-spirooxindoles via a 1,3-dipolar cycloaddition reaction of chromones 1 with azomethine ylides (thermally generated in situ from isatins and proline or thioproline). Another valuable application of this method was for the less reactive chromone through a carboxylic acid-activation and then decarboxylation strategy, which enabled diversity-oriented synthesis of complex pirooxindoles bearing four contiguous stereocenters (one of which is a spiro quaternary stereocenter) with high efficiency and stereoselectivity (up to 90% yield and 20:1 d.r.). This protocol could provide libraries of stereochemically rich and multiple pharmecore collections, that will help in search for new drug-like molecules.     

Interaction of metal ions with poly(1,3-propylene phosphate) — a synthetic analogue of natural teichoic acids

The binding of metal ions to poly(1,3-propylene phosphate), (PPP), which can be considered as a synthetic analogue of natural teichoic acids, was examined. Infrared spectra of PPP in different ionic forms and of different degrees of polymerization were analyzed and some information on metal ion binding modes in M(I)-PPP and M(II)-PPP complexes, both in the condensed state as well as in aqueous solution, was obtained. It is concluded that the binding modes of sodium, potassium, cesium, calcium, and magnesium ions to phosphate groups of PPP are the same or similar and/or complexes of the same or similar structure are formed. In aqueous solution the analyzed metal ions are bound to poly(alkylene phosphate) chains mainly in the form of outer sphere complexes.     

Redox deracemization of α-substituted 1,3-dihydroisobenzofurans

Chiral α-substituted 1,3-dihydroisobenzofurans are key scaffolds in a number of bioactive natural products and synthetic pharmaceuticals. However, catalytic asymmetric approaches have been rarely developed. Here, a redox deracemization technology is adopted to address the catalytic asymmetric synthesis. A broad range of α-aryl substituted 1,3-dihydroisobenzofurans are effectively deracemized in high efficiency with excellent ee. α-Alkynyl substituted ethers were also compatible with the deracemization technology.     

Synthesis of Novel 1,3-Dioxolane Nucleoside Analogues

Novel 1,3-dioxolane C-nucleoside analogues of tiazofurin 2-(2-hydroxymethyl-1,3-dioxolan-4-yl)-1,3-thiazole4-carboxamide as well as N-nucleoside analogues of substituted imidazoles 1-(2-hydroxymethyl-1,3-dioxolan4-yl)-4-nitroimidazole and 1-(2-hydroxymethyl-1,3-dioxolan-4-yl)-4,5-dicyanoimidazole were synthesized from methyl acrylate through a multistep procedure. Their structures were confirmed by IR,^1H NMR,^13C NMR spectraand elemental analysis.     

Synthesis of Sterically Hindered 1,3‐Diketones

An efficient and practical method for the synthesis of sterically hindered aliphatic/aromatic 1,3‐diketones via coupling of ketones with esters using potassium tert‐butoxide is described. The protocol requires milder operating conditions, and the products are obained in good to excellent yields.