A facile synthesis of α,α,ω,ω-tetrahalo-α,ω-dicarboxylic esters

The synthesis of some α,α,ω,ω-tetrachloro and tetrabromo-derivatives of the hypolipidemic 3,3,14,14-tetramethylhexadecanedioic acid from α,ω-dihalo-esters, carbon tetrahalides and lithium diisopropyl amide has been described. Interaction of α,ω-dichloro esters with CBr₄ was shown to give the expected α,ω-dibromo-α,ω-dichloro compounds, but treatment of bis(l-methylethyl) 2,15-dibromo-3,3,14,14-tetramethylhexa-decanedioatewith CCl₄ was found to result in halogen exchange yielding the tetrachloro-diester as the major product.     

Mono-Protected Diamines. N-tert-Butoxycarbonyl-α,ω-Alkanediamines from α,ω-Alkanediamines

We wish to report a convenient pathway to N-tert-butoxycarbonyl-α,ω-alkanediamines 2a-e [H₂N(CH₂)χNHBOC; χ=2, 3, 4, 5 and 6; (75–90% yields)] by treatment of the corresponding α,ω-alkanediamine with di-tert-butyl dicarbonate in dioxane as the solvent. Only small amounts of the bis-substituted N.N′-tert-butoxycarbonyl-α,ω-alkanediamines 3a-e were formed (2–9%) which were easily removed by an aqueous workup. The α,ω-alkane-aza-diamine 4 was also mono-protected (62% yield of 5) by the same methodology.     

Synthesis of symmetrical acetylenic hydrocarbons and their α,ω-di-derivatives from α,α,α-trichloro- and α,α,α,ω-tetrachloro-alkanes

Summary By the action of sodium in xylene on polychloro hydrocarbons containing -CCl₂-CCl₂- or- CC1=CC1-, groupings the corresponding symmetrical acetylenic hydrocarbons containing 10,14, and 18 carbon atoms in the molecule were obtained. From ,-disubstituted tetrachloroalkanes by the same method 1,10-diethoxy-5-decyne, 1,14-diethoxy-7-tetradecyne, and 1,14-bisdiethylamino-7-tetradecyne were obtained.The spectra were determined in the Optical Laboratory of the Institute of Heteroorganic Compounds of the USSR by N. A. Chumaevskii, who we thank.     

Electrochemical oxidation of tetramethyl esters of α,α,ω,ω-alcaneteracarboxylic acids

Cyclization of esters of butane-1,1,4,4- and pentane-1,1,5,5-tetracarboxylic acids during electrolysis in methanol in the presence of Nal produces, with a yield of 95%, the esters of cyclobutane-1,1,2,2- and cyclopentane-1,1,2,2-tetracarboxylic acids. Under similar conditions, esters of the highest ,,,-alkanetetracarboxylic acids undergo iodation and hydroxymethylation due to electrical oxidation of methanol to formaldehyde. During electrolysis in methanol in the presence of NaOAc, the esters of ,,,-alkanetetracarboxylic acids undergo effective hydroxymethylation, followed by cyclization into substituted five- and six-member lactones, or tetrahydrofurans when structurally possible.N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 10, pp. 2332–2339, October, 1992.     

Synthesis and characterization of α,ω-dichloro-polymethylphenylsilane

The synthesis of a functional polysilane, α,ω-dichloro-polymethylphenylsilane (α,ω-dichloro-PMPS), based on the Wurtz-type reductive coupling, has been considered. A study of some reaction parameters shows that both yield and molecular weight distribution of α,ω-dichloro-PMPS can be greatly influenced by the work-up conditions, reaction time, monomer concentration and temperature during the initiation of the polymerization. By varying the synthesis conditions, different ratios of high and low molecular weight fractions were obtained. Samples of different molecular weight were isolated by fractional precipitation of the crude polymers. The chlorine-end functionalization was confirmed by ²⁹Si NMR spectroscopy and the concentration of end-groups was quantitatively determined by elemental analysis of chlorine.     

Long-chain α,ω-bisisothiocyanates from a marine sponge

Eighteen long-chain aliphatic α,ω-bisisothiocyanates were isolated from a marine sponge, Pseudaxinyssa sp. from Fiji. Eight compounds are di-, ten are monolefinic. Three additional constituents are α-isothiocyano-ω-formyl compounds.     

Elimination Reaction of α,ω-Diols by Magnesium

Inrecentyears,someapplicationsofmagnesiuminorganicsynthesisandorganosiliconreactionshavebeenreported""'.Here,wewishtoreportanothernewreaction,theelindnationreactionofsomediolsbymagnesium.Inthepresenceofiodine,l,3-propanediol,l,4-butanediolorl,5-pentanediolreactswithmagnesiumtoproducemagnesiumalkoxides.Whenthemixtureofformedmagnesiumalkoxideinalcoholwasrefluxed,thermaldecompositionoccurswiththeformationofcyclicethersand,respectively,allylalcohol,buten-l-olandpenten-l-ol.Thetotalreactioncorrespo…     

An improved method for preparing α,ω-dinitroalkanes

Summary We have suggested an improved method for preparing , -dinitroalkanes which consists in the action of silver nitrite on , -dibromoalkanes in petrofeum ether medium with heating.     

Some peculiarities of hydrosilylation of α,ω-divinyloligosilanes

The stability of Si-Si bonds in linear and cyclic permethyloligosilanes and in ,-divinyloligosilanes under conditions of hydrosilylation in the presence of the Speier's catalyst was studied. Polycarbosilanes containing silylene fragments in their backbone chains were prepared by the reaction of 1,4-bis(dimethylsilyl)benzene with ,-divinyloligosilanes. It was found that the structure of these polymers is disturbed due to the side reaction involving the cleavage of the Si-Si bond in vinyloligosilanes under the action of H₂PtCl₆.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2547–2549, October, 1996.     

Analysis of {α,ω-Dichloroalkane or α,ω-Dibromoalkane] + Benzene and α,ω-Dichloroalkane + Tetrachloromethane} Mixtures in Terms of Group Contributions

Abstract

Molar excess enthalpies, H ^E _m, at 298.15K and atmospheric pressure have been determined for three binary liquid mixtures [x{1,3-dichloropropane or 1,4-dichlorobutane and 1,6-dichlorohexane} + (1 - x) tetrachloromethane]. These experimental results along with the data available in the literature on molar excess Gibbs energies, G ^E _m, activity coefficients at infinite dilution, In γ^∞ _i , and molar excess enthalpies, H ^E _m, for α,ω-dihaloalkanes + benzene or + tetrachloromethane mixtures are examined on the basis of the DISQUAC group contribution model.     

N α,N ω-DIPHOSPHONO-, DIPHOSPHINO-METHYL-L-α,ω-DIAMINOCARBOXYLIC ACIDS

Abstract

Treatment of N-hydroxymethylated lactames 1,4-diamino-L-butanoic acid–1, L-ornithine–2, and L-lysine–3 is carried out with phosphorus trichloride to give the phosphonic acids 4, 5 and 6, and with methyldichlorophosphine to give the methylphosphinic acids 7, 8 and 9, which after alkaline hydrolysis liberate the carboxylic acids 10–15. Analogously, from the L-lysine derivative–16 and the aminomethylphosphonic acid derivative 18, the acids 15 and 19 are obtained after hydrolysis. The herbicidal activity of the lysine derivative 15 is established.     

A Multi-armed Neutral Receptor for α,ω-Dicarboxylate Anions

A multi-armed neutral anion receptor (1) bearing multiple amide and thiourea binding sites was synthesized. Receptor 1 forms 1:2 complexes with dicarboxylate anions, and the sensitivity for recognition of dicarboxylate depends strongly on the chain length of these dicarboxylate anions. Addition of the anions caused a considerable change in the absorbance and fluorescent intensity of the host solution and a consequent visible color change.