Intermediacy of silylene and germylene in direct synthesis of organosilanes and organogermanes

In the direct synthesis of silicon compounds by reactions of elemental silicon with methyl chloride, methanol and hydrogen chloride, silylene formed on surface of silicon grains during the reaction is an intermediate. The reaction of surface silylene with a variety of unsaturated hydrocarbons provides new direct synthesis of organosilanes. In the direct synthesis of methylchlorogermanes from elemental germanium, surface germylene is not an intermediate, while tetrachlorogermane is synthesized by the direct reaction of germanium with hydrogen chloride via dichlorogermylene intermediate. Various unsaturated hydrocarbons or organic chlorides added to the system of tetrachlorogermane synthesis give new methods for the synthesis of organogermanes.     

Intermediacy of silylene and germylene in direct synthesis of organosilanes and organogermanes

In the direct synthesis of silicon compounds by reactions of elemental silicon with methyl chloride, methanol and hydrogen chloride, silylene formed on surface of silicon grains during the reaction is an intermediate. The reaction of surface silylene with a variety of unsaturated hydrocarbons provides new direct synthesis of organosilanes. In the direct synthesis of methylchlorogermanes from elemental germanium, surface germylene is not an intermediate, while tetrachlorogermane is synthesized by the direct reaction of germanium with hydrogen chloride via dichlorogermylene intermediate. Various unsaturated hydrocarbons or organic chlorides added to the system of tetrachlorogermane synthesis give new methods for the synthesis of organogermanes.     

Organomagnesium Synthesis of <Emphasis Type="Italic">sec</Emphasis>-Butyl- and <Emphasis Type="Italic">tert</Emphasis>-Alkylchlorogermanes and Their Reaction with Ethynylmagnesium Bromide

The limits of application of organomagnesium synthesis to the substitution of chlorine atoms in tetrachlorogermane with bulky alkyl groups are established. The reaction of tetrachlorogermane with 2-butylmagnesium chloride leads to the substitution of one, two, or three chlorine atoms, yielding the corresponding alkylchlorogermanes (MeEtCH)_nGeCl_4-n . The reaction of GeCl₄ with tert-alkylmagnesium halides leads to the substitution of only one chlorine atom, yielding tert-alkyltrichlorogermanes RMe₂CGeCl₃ (R = Me, Et, Bu). tert-Butyltrichlorogermane reacts with ethylmagnesium bromide to give ethyl(tert-butyl)dichlorogermane. Isopropyltrichlorogermane reacts with tert-butylmagnesium chloride to give isopropyl(tert-butyl)dichlorogermane. This shows that the organomagnesium synthesis does allow linking of two bulky substituents to the germanium atom. The reaction of tert-alkyltrichlorogermanes and 2-butyltrichlorogermane in THF with ethynylmagnesium bromide, in which the hydrocarbon group is the most sterically accessible, allows substitution of all the three chlorine atoms, yielding the corresponding alkyl(triethynyl)germanes. The latter compounds react with the Grignard reagent and trimethylchlorosilane to give the corresponding alkyl(trimethylsilylethynyl)germanes.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 5, 2005, pp. 757–761.Original Russian Text Copyright © 2005 by O. Yarosh, Voronkov, Zhilitskaya, N. Yarosh, Albanov, Korotaeva.     

纳米钯催化苄基氯代物与烯丙基硼酸频哪醇酯的羧化Suzuki偶联反应

CO2是廉价的C1源,同时具有无毒、储量丰富的优点, 符合绿色化学发展要求. 利用 CO2构筑新的 C–C 键是化学固定CO2的重要方法. Β,γ-不饱和酯类结构单元是许多生物活性分子的重要组成部分, 经由双π-烯丙基钯中间体与 CO2反应, 合成新的β,γ-不饱和酯类化合物, 具有重要意义. CO2与有机硼化合物的羧化反应已有报道, 有机硼化合物具有低毒、对水不敏感等优点. 但是已报道的羧化 Suzuki 偶联反应存在诸多缺点: (1) 需要使用含膦或者氮杂环卡宾配体的催化剂, 而这些催化剂的制备过程使前期实验步骤变得冗长, 同时反应液的酸化后处理过程也会造成环境污染; (2) 有机硼试剂的官能团兼容范围窄, 限制了底物范围的拓展. 本课题组以原位生成的纳米钯粒子为催化剂, 在 CO2存在的温和条件下, 高效实现了苄氯与烯丙基硼酸频哪醇酯的羧化 Suzuki 偶联反应. 反应过程中无其它配体加入, 反应结束后不需要酸化或酯化的后处理过程. 该反应将具有广泛的官能团兼容性.本文以 TBAB 稳定的纳米钯粒子为催化剂, 在温和条件下, 实现了氯甲基芳香化合物、烯丙基硼酸频哪醇酯和 CO2的三组分羧化 Suzuki 偶联反应. 最佳反应条件为: Pd(acac)2(5 mol%)、TBAB (0.7 mmol, 1.4 equiv.)、KF (1 mmol, 2.0 equiv.)、苄基卤代物 (0.5 mmol)、烯丙基硼酸频哪醇酯 (0.6 mmol, 1.2 equiv.)、CO2(2.0 Mpa)、溶剂 THF (5 mL), 50 oC 反应 24 h. 在最佳反应条件下, 苯环、萘环以及杂芳环的氯甲基化合物均可发生该羧化反应. 苯环上取代基的位置对产物的收率有影响. 当使用 1-溴甲基萘作为底物时反应也能够发生, 收率与 1-氯甲基萘作为底物时的收率相当. 与已报道有机硼试剂的羧化反应相比, 该反应体系无需加入配体, 原位生成了纳米钯粒子, 避免了催化剂或者配体的复杂制备过程. 该反应中, 氟离子的存在是必要的, 对烯丙基硼酸频哪醇酯具有活化作用.     

DIALKYL THIOPHOSPHONATE DERIVATIVES OF TRIORGANOTIN(IV)

Abstract

The reaction of triorganotin chlorides with sodium dialkyl thiophosphites proceeds to completion on refluxing the reactants in a 1:1 molar ratio for about ten hours. Similar reactions of triorganotin chloride with dialkyl thiophosphonate do not give comparable yields in the presence of triethylamine. The products formed are colorless volatile liquids having pungent odour, are miscible with common organic solvents and are found to be monomeric. Exposure of these compounds to atmospheric oxygen the thiophosphite [Sn-S-P] linkage was oxidized to a thiophosphate [Sn-O-P(S)] linkage. These complexes have been characterized by elemental analyses, molecular weight determination, IR, ¹H NMR and ³¹P NMR spectral data.     

6-羟基富烯及环戊二烯并[d]哒嗪的合成

本文以6, 6-二烷基富烯与烯丙基格氏试剂反应所得的取代环戊二烯基负离子与芳酰氯反应, 合成了5个新的6-羟基富烯化合物(1-5)。用此化合物与肼反应, 合成了5个新的环戊二烯并[d]哒嗪化合物(6-10)。通过^1H NMR、IR及元素分析确定了它们的结构。     

Reaction of allylsilanes and allylstannanes with alkynes catalyzed by electrophilic late transition metal chlorides

The intramolecular reaction of allylsilanes and allylstannanes with alkynes proceeds catalytically in the presence of Pt(II), Pd(II), Ru(II), and Au(III) chlorides. Although more limited, AgOTf also catalyzes the cyclization. Usually, PtCl2 as the catalyst in methanol or acetone gives the best results. The reaction proceeds by exo attack of the allyl nucleophile on the alkyne to form five- or six-membered ring carbocycles. The reaction generally proceeds with anti stereoselectivity. However, a terminally substituted trimethylsilyl derivative reacts by a syn-type addition. The intermediate alkenylpalladium complex has been trapped with allyl chloride to form an allylated derivative with an additional carbon-carbon bond.     

β-KETOSULFINYL CHLORIDES AND RELATED COMPOUNDS

Abstract

Isopropyl β-ketosulfinyl chlorides may be prepared in high yields by treating the appropriate isopropyl ketone with thionyl chloride under mild conditions. β-Ketosulfinyl chlorides do not appear to have been previously reported in the literature. Analytical and spectral data indicate that in cases where α and α' protons are adjacent to the carbonyl group only the α-proton of the isopropyl group is substituted giving a monosulfinyl chloride. In certain cases where the α'-proton is activated cyclization and reduction may occur to give the substituted thietan-3-one. Comparable chloro-compounds have been prepared by treating the ketone with sulfuryl chloride. Anomalous nmr spectra obtained for certain compounds have been further studied using variable temperature techniques and various solvents. An attempt was made to prepare the β-ketosulfinamides, and the compounds obtained were found to be unstable.     

The rearrangement of cyclopropyl chlorides to allyl chlorides : Stereospecificity in the recapture of the chloride ion

The cyclopropyl chlorides (1 and 2) rearrange on heating to give stereospecifically the allyl chlorides (3 and 4, respectively). In the presence of nucleophiles such as methoxide ion, the corresponding allyl ethers (5 and 6, respectively) are formed. Analysis of the stereochemistry of these products indicates that they are formed from the corresponding allyl chlorides (3 and 4), which are evidently the first-formed products of the reaction even in the presence of strong nucleophiles. The reaction of the allyl chlorides (3 and 4) with sodium phenylthioxide in aprotic non-polar solvents goes predominantly with retention of configuration, but in methanol is normal in giving predominantly inversion of configuration.     

Transition metal-free tandem pyridinyl–allyl–allyl cross-coupling reaction

A transition metal-free, direct one-pot domino allylation reaction of 2-pyridinyl Grignard reagents with polysubstituted allyl chlorides for the regioselective synthesis of pyridinyl-substituted 1,5-diene derivatives has been disclosed. The reaction presumably proceeded through the coupling of polysubstituted allyl chloride to 2-PyMgX, which was in situ generated from 2-bromopyridine with i-PrMgCl·LiCl.     

Recent progress of synthesis of new arylazoazoles based on bis(carbothioamides)

In this study, new bisthiazoles were efficiently synthesized from the reaction of hydrazine-1,2-bis(carbothioamide) with N-aryl-2-oxopropanehydrazonoyl chlorides or N-aryl C-ethoxycarbonyl methanehydrazonoyl chlorides. The formation of the final compounds starts by nucleophilic attack of thiolates to give S-alkylated intermediate, which in situ undergoes nucleophilic addition and intramolecular cyclization to give the final products as described in the synthetic schemes. The inexpensive and simple reaction conditions, commercial availability of the reagent, good yields and excellent purities of the products make this method valuable from a preparative point of view. Furthermore, the antibacterial activities values of the new compounds were evaluated against Gram-positive and Gram-negative microorganisms. The final products were identified and characterized by elemental analysis, Fourier transforms infrared spectroscopy (FT-IR), mass spectrometry (MS), and nuclear magnetic resonance (NMR).     

The Transition State of Free Radical SH2′ Reaction of Allyl Chloride with Organomercurial Study by Inverse Secondary α‐Deuterium Kinetic Isotope Effect

The concerted mechanism of free radical S_H2′ reaction of 2‐substituted allyl chloride was suggested again by inverse secondary α‐deuterium isotope effect. The transition state of free radical S_H2′ reaction of allyl chlorides seems to be symmetrical and is not as early as that of a free radical addition reaction.     

Synthese funktioneller Carbonsäure-Silylester

Synthesis of Functional Carboxylic Acid Silylester Di-tert-butylsilandiol reacts with organic acid chlorides to chlorosilanoles R₂Si(OH)Cl 1 (R = t-Bu). The phosphoric acid silylester 2 is obtained from 1 and POCl₃. Lithiated halogenosilanoles react with carboxylic acid chlorides to give silylesters ( 3 – 7 ). Lithium (trimethyl-acetoxy)silanolate 8 is obtained in the reaction of the lithiated diol with the chloride of trimethylacetic acid. The analogous reaction with benzoyl chloride lead to the formation of the bis(benzoic acid) silylester 9 . The condensation product 10 is obtained in the reaktion of the lithiated aminosilanol (t-Bu)₂Si(NH₂)OLi with trimethylacetic acid chlorid and condensation of the formed ester with aminosilanol.     

Linear polythioesters. IX. Products of interfacial polycondensation of 4,4′-dimercaptobenzophenone with some aliphatic acid dichlorides

By interfacial polycondensation of 4,4′-dimercaptobenzophenone with oxalyl, succinyl, adipolyl, suberoyl, and sebacoyl chlorides new polythioesters were obtained. To determine the optimal conditions of interfacial polycondensation the influence of the following factors on yield and value of reduced viscosity was studied: type of organic phase, the quantitative ratio of aqueous to organic phase, concentration of hydrogen chloride acceptor, molar ratio of reagents, temperature of reaction, rate of acid chloride addition, and contribution of catalyst. A thorough examination of the polycondensation of dithiol with adipolyl and sebacoyl chlorides was carried out. The structure of all polythioesters obtained under model conditions was determined by elemental analysis and infrared spectra. Initial decomposition and intensive decomposition temperature were defined by the curves of thermogravimetric analysis. Mechanical and electrical properties of the polythioesters obtained from 4,4′-dimercaptobenzophenone and adipoyl and sebacoyl chlorides were determined. The molecular weight was not measured because of the low solubility of the polythioesters.     

Synthese von Germanium(I)‐bromid. Ein erster Schritt zu neuen Clusterverbindungen des Germaniums?

Synthesis of Germanium(I) Bromide. A First Step towards New Gemanium Cluster Compounds? Thermodynamic data for gaseous GeBr, derived from quantum chemical (DFT)‐calculations show that this monohalide should be formed at 1550 °C as a product of the reaction of elemental germanium with HBr at 1×10^—2 mbar. Herein the design of an apparatus is described in which GeBr can be synthesized under these conditions and cocondensed with toluene at —196 °C. Using this technique 3 g of a dark red X‐ray amorphous solid could be prepared over a period of 3 hours and was identified to be GeBr. It is shown to undergo disproportionation at 90 °C to give elemental germanium and germanium tetrabromide.     

First practical synthesis of formamidine ureas and derivatives

Isonitriles and ureas undergo a condensation reaction in the presence of acid chlorides to give formamidine ureas, for which no general synthetic routes currently exist. A mechanism is proposed in which the key intermediate is an electrophilic adduct of isonitrile and acid chloride. The process is tolerant of moderate variability in the nature of the components, and access to formamidine ureas of varying substitution patterns is further enhanced by a facile exchange reaction with amines. [reaction: see text]     

Chalcogeno[bis(phosphaalkenyl)] germanium and tin compounds

The first diphosphaalkenylstannylene stabilized through complexation with a carbene NHC-Sn[C(Cl)═PMes*](2)1 (Mes* = 2,4,6-tri-tert-butylphenyl; NHC = :C{N(iPr)C(Me)}(2)) was isolated and fully characterized including single crystal X-ray diffraction analysis. Its reaction with elemental sulfur rapidly gives the cyclic Sn(2)S(2) (dithiadistannetanne) derivative 3, presumably formed by dimerization of a stannathione intermediate. By contrast, its germanium analogue NHC-Ge[C(Cl)═PMes*](2)7 leads to the corresponding monomeric germathione 4 and germaselenone 5. The germaselenone was more stable than the germathione and could be structurally characterized. An unusual thermal cyclization reaction of the last one occurs with an excess of selenium to give the Ge(2)Se(3) (triselenadigermolane) ring derivative 6.     

Reactions of chloromethyloxirane and dihalopropanols with chalcogens in basic reducing systems

Chloromethyloxirane and 2,3-dibromopropan-1-ol reacted with a solution of selenium or tellurium in the system hydrazin hydrate-potassium hydroxide (K₂Se₂, K₂Te₂) to give allyl alcohol; the reaction was accompanied by regeneration of the initial free chalcogen. 1,3-Dichloropropan-2-ol reacted with selenium in the same system to give oligomeric product having a 2-hydroxypropane-1,3-diyldiseleno monomeric unit, while the reaction with tellurium led to the formation of allyl alcohol and almost complete regeneration of initial tellurium. Probable reaction mechanisms are discussed. Polyselenide oligomers containing a hydroxy group in a monomeric unit were formed in reactions of chloromethyloxirane and 1,3-dichloropropan-2-ol with selenium in the system hydrazine hydrate-2-aminoethanol. Under analogous conditions 2,3-dibromopropan-1-ol was converted into allyl alcohol with regeneration of elemental selenium. Reductive cleavage of polyselenide oligomers gave Se-methyl derivatives of 2-hydroxypropane-1,3-diselenol.     

Synthesis and structure of new types of organogermanium compounds containing α‐amino acid or α‐aminophosphonic acid moieties

A series of germasesquioxides and germatranes containing α‐amino acid or α‐aminophosphonic acid moieties was synthesized by the reaction of β‐trichlorogermylpropionyl chloride with α‐amino acid esters or α‐aminophosphonates. The structures of all products were confirmed by ¹H NMR, ³¹P NMR, and IR spectra, and elemental analyses. The intramolecular monocyclic penta‐coordinated structure of the trichlorogermyl intermediate was determined by X‐ray diffraction. The X‐ray analyses showed that the geometry about the germanium atom was a slightly distorted trigonal bipyramid, and a coordinate covalent bond exists between the oxygen and the germanium atoms. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 73–78, 1999     

Origin of the regio- and stereoselectivity in palladium-catalyzed electrophilic substitution via bis(allyl)palladium complexes

Palladium-catalyzed allylic substitution of aryl allyl chlorides with aromatic and heteroaromatic aldehydes was performed in the presence of hexamethylditin. This procedure involves palladium-catalyzed formation of transient allylstannanes followed by generation of a bis(allyl)palladium intermediate, which subsequently reacts with the aldehyde electrophile. The catalytic substitution reaction proceeds with high regio- and stereoselectivity. The stereoselectivity is affected by the steric and electronic properties of the allylic substituents. Various functionalities including NO(2), COCH(3), Br, and F groups are tolerated under the applied catalytic conditions. Density functional calculations at the B3PW91/DZ+P level of theory were applied to study the steric and electronic effects controlling the regio- and stereoselectivity of the electrophilic addition. The development of the selectivity was studied by modeling the various bis(allyl)palladium species occurring in the palladium-catalyzed substitution of cinnamyl chloride with benzaldehyde. It was found that the electrophilic attack proceeds via a six-membered cyclic transition state, which has a pronounced chair conformation. The regioselectivity of the reaction is controlled by the location of the phenyl group on the eta(1)-allyl moiety of the complex. The stereoselectivity of the addition process is determined by the relative configuration of the phenyl substituents across the developing carbon-carbon bond. The lowest energy path corresponds to the formation of the branched allylic isomer with the phenyl groups in anti configuration, which is in excellent agreement with the experimental findings.