Substitution reactions of some polynuclear carbonyl anions

The reactions of [FeCo₃(CO)₁₂]^- and [MnFe₂(CO)₁₂]^- with a number of monodentate phosphorus donor ligands (L) are reported, and complexes of the type [FeCo₃(CO)₁₁L]^- and [MnFe₂(CO)₁₁L]^- have been isolated and characterised. Only with Ph₂PCH₂CH₂PPh₂ (DPPE) was it possible to replace more than one CO group, the complex [FeCo₃(CO)₁₀(DPPE)]^- being obtained. Protonation of the ironcobalt anions leads to the neutral hydrido clusters and is accompanied by a large kinetic isotope effect, although not as large as for [FeCo₃(CO)₁₂]^- itself. The reaction of [FeCo₃(CO)₁₂]^- with Ph₂C₂ gives [FeCo₃(CO)₁₀(Ph₂C₂)]^-.     

A new method for the hydroxymethylation of carbonyl compounds

Benzyl chloromethyl ether reacts with carbonyl compounds in the presence of SmI₂ to afford alcohols (I), which are subsequently subjected to hydrogenolysis to yield diols (II).     

A new method for the preparation of 2-thio substituted furans by methylsulfanylation of gamma-dithiane carbonyl compounds

Several related methods for the preparation of differentially substituted 2-thiofurans are described. The general procedure involves the formation of a thionium ion from a gamma-dithianyl substituted carbonyl compound followed by cyclization of this reactive intermediate onto the tethered carbonyl group. Two methods for thionium ion generation were explored. One of these involved an acid-catalyzed reaction of beta-ketenedithioacetals, prepared from the condensation of 2,2-bis(methylsulfanyl)acetaldehyde with a variety of ketones. Cyclization followed by loss of methane thiol gave 2-thiofurans 17, 18 and 23, 24 in 70-90% yield. Attempts to prepare 5-heteroatom substituted 2-thiofurans from the corresponding beta-ketenedithioacetal amides or esters were unsuccessful, leading to 1,2-thio rearranged products. A more successful route involved the reaction of beta-acetoxy-gamma-thianyl carbonyl compounds with dimethyl(methylthio)sulfonium tetrafluoroborate (DMTSF). Treatment of the dithiane with this reagent resulted in the smooth generation of a thionium ion. Cyclization followed by loss of acetic acid afforded thiofurans 17, 18, 23, 47-49, 51, and 61-64 in 40-100% yield. The N-butenyl substituted thioamido furan furnished a rearranged hexahydropyrroloquinolin-2-one in high yield when heated at 110 degrees C.     

A new method for the preparation of polyfluoroalkanedithiocarboxylates

A new method for synthesis of alkyl and aryl polyfluoroalkyldithiocarboxylates by reaction of 1,1-dichloropolyfluoroalkylsulfenylchlorides with mercaptans in the presence of ZnCl₂ was developed. The sulfenylchlorides are easily obtained by chlorination of benzyl 1,1-dihydropolyfluoroalkylsulfides or benzyl dithioacetals of polyfluoroaldehydes.     

A new method for preparation of dihydrodinaphthopyranopyrans

The syntheses of 7a,15a-dlhydro-15a-methylnaphtho[2,l-b] naphtho [1',2':5,6] pyrano[3,2-e]pyran (II) and 7a,15a-dihydro-7a-methyl-15a-isopropyi naphtho [2,1-b] naphtho [1' ,2' : 5,6] pyrano [3,2-e] pyran (III) from 2-naphthol and corresponding dimethylol ketones in one step were described. Amberlyst-15® was used as catalyst.     

A new method for the preparation of diphenylboryldipivaloyl phosphide

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2670–2671, November, 1990.     

A new method for the preparation of modified oligonucleotides

[reaction-see text] N-Nitrothymidine can be transformed into a phosphoramidite building block suitable for oligonucleotide synthesis using the standard phosphite triester solid-phase approach. The N-nitrothymidine residues remain stable during the elongation cycles and react smoothly with primary amines, furnishing oligonucleotides containing N3-modified thymidines. A number of N3-substituted oligonucleotides have been prepared using this methodology, some of them incorporating aminoalkyl or hydroxyalkyl groups.     

A new general method for the preparation of N-sulfonyloxaziridines

[reaction: see text] A simple procedure to obtain N-alkylsulfonyl- and N-arylsulfonyloxaziridines from the corresponding N-sulfinylimines involving a one-pot, two-step oxidation process with m-CPBA (1 equiv) and m-CPBA/KOH (1.1 equiv) is reported. The method is applicable to N-sulfinylimines derived from aldehydes (aliphatic and aromatic) and ketones (dialkyl and aryl alkyl) and preserves C=C-conjugated double bonds. Almost quantitative yields, very mild conditions (usually less than 5 min at room temperature), and easy purification by filtration are the main features of this new procedure, which can be performed at a gram scale.     

A new method for the preparation of perfluorocarboxylic acids

The reaction of both primary perfluoroalkyl iodides and bromides containing 3 ∼ 12 carbon atoms [CF₃(CF₂)_nX, n = 2 ∼ 11, X = Br, I] with a Rongalite-NaHCO₃ reagent in aqueous dipolar aprotic solvents, such as DMF or DMSO, has been investigated. The reaction gave sodium perfluorocarboxylates [CF₃(CF₂)_n-1CO₂Na, n = 2 ∼ 11] in 51 – 86 % yields, and these were transformed to the respective perfluorocarboxylic acids [CF₃(CF₂)_n−1CO₂H, n = 2 ∼ 11] by treatment with sulfuric acid. This provides a new method for the synthesis of perfluorocarboxylic acids.     

A new method for the preparation of diphenylmethyl ethers

Various diphenylmethyl ethers are prepared under mild conditions by using tri-diphenylmethyl phosphate as alkylating agent. O-Diphenylmethyl-L(?)-Lactic Acid is prepared by this method.     

A novel synthetic method for preparation of some folates

An improved method was developed for preparation of 5,6,7,8-tetrahydrofolic acid (THF) and calcium-5-methyltetrahydrofolate (5-MTHF-Ca) by reduction of folic acid using KBH₄ catalyzed by Pb(NO₃)₂. The yields of THF and 5-MTHF-Ca were 56.5 and 42.7 %, respectively. A convenient method for measurement of THF and 5-MTHF-Ca using liquid chromatography–mass spectrometry (LC–MS) was also established, enabling analysis of those folates within 10 min without application of gradient elution.     

A new method for the preparation of α-(perfluoroalkyl) carbonyl and γ-(perfluoroalkyl)-α,β-unsaturated carbonyl compounds

R_fI(Ph)OSO₂CF₃ or R_fI(Ph)OSO₃H smoothly reacted with various trimethylsilyl enol ethers under mild conditions to give α-(perfluoroalkyl) carbonyl and γ=(perfluoroalkyl)-α,β-unsaturated carbonyl compounds in high yields.     

Stereoselective ring-opening reactions with AcBr and AcCl. A new method for preparation of some haloconduritols

The actions of AcX (X=Br, Cl) on 7-oxa-bicyclo[2.2.1]hept-5-ene-2,3-diol diacetates and a transoid-epoxide prepared from the acetonide of cyclohexa-3,5-diene-cis-1,2-diol were studied. H₂SO₄-catalyzed cleavage of exo-cis-7-oxa-bicyclo[2.2.1]hept-5-ene-2,3-diol diacetate with AcCl gave (1α,2α,3α,6β)-6-chloro-4-cyclohexene-1,2,3-triol triacetate, from which the corresponding chloroconduritol was obtained by trans-esterification (MeOH/HCl). A similar reaction of the exo-diacetate with AcBr in the presence of H₂SO₄ resulted in bromine addition. The formation of bromine from the reaction of AcBr and H₂SO₄ was observed by independent experiments. H₂SO₄-catalyzed reaction of endo-cis-7-oxa-bicyclo[2.2.1]hept-5-ene-2,3-diol diacetate with AcX (X=Br, Cl) gave (1α,2α,3β,6β)-6-halo-4-cyclohexene-1,2,3-triol triacetates. The reaction of the transoid-epoxide with AcX (X=Br, Cl) with no catalyst gave also (1α,2α,3β,6β)-6-halo-4-cyclohexene-1,2,3-triol triacetates.     

A new method for99mTc generator preparation

The authors report here a new approach for making^99mTc generators based on neutron irradiation of metallic molybdates and direct elution eliminating intermediate chemical processing steps. This approach tested using zirconium molybdate was found to yield^99mTc with good yield and purity. This seems to be the simplest way of making column type^99mTc generator even using low flux reactors and merits further detailed evaluation.     

由苯制备环己醇新途径

将可溶性Ru纳米粒子用于催化苯选择性加氢制备环己烯反应,考察了还原方法对Ru纳米粒子催化活性的影响;并以醇水还原法制备的Ru纳米粒子为催化剂,考察了温度和压力对反应性能的影响.当使用脱硫的苯作为原料时,苯转化率可达30.2%,环己烯选择性达到46.9%.以无水兰尼镍作催化剂,100oC时,环氧环己烷加氢转化率为100%,环己醇选择性为93.2%.从原料苯出发制得环己醇的单程收率可达14%,由此找到一条制备环己醇的新途径.     

A new method for preparation of magnetic polymer particles

Synthesis of magnetic polymer particles (MPP) was carried out through two steps. Firstly, the iron oxide particles carrying vinyl groups were synthesized, and in the second step, styrene (ST), divinyl benzene (DVB), and 2-hydroxyethyl methacrylate (HEMA) were polymerized on the surface of modified iron oxide through an emulsifier-free emulsion polymerization technique. The final particles were characterized by a Fourier transform infrared spectroscopy (FTIR), Fourier transform infrared attenuated total reflectance spectroscopy (FTIR-ATR), X-ray diffractometer (XRD), thermal gravimetry analysis (TGA), Fritsch particle sizer, scanning electron microscope (SEM), and vibrating sample magnetometer (VSM). Experimental analysis confirmed that all the iron oxide particles were embedded in a polymer phase and the final particles have more than 67 % iron oxide content. According to magnetometry data, the shape of the hysteresis loops evidences the ferromagnetic character of the particles.     

A new method for the preparation of solution of sodium pentaphosphacyclopentadienide

Heating of a mixture of white phosphorus and sodium in diethylene glycol dimethyl ether in the presence of catalytic amounts of dibenzo-18-crown-6 affords a pure solution of sodium pentaphosphacyclopentadienide NaP₅. One of the intermediate products is trisodium heptaphosphide Na₃P₇. The influence of the nature of a metal (Li, Na, K) on the formation of the pentaphosphacyclopentadienide anion was studied. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1249–1251, July, 2006.