共查询到20条相似文献,搜索用时 0 毫秒
1.
2.
3.
4.
5.
[reaction: see text]. Dynamic gas-phase thermoisomerization (DGPTI) of medium- and large-ring 3-vinylcycloalkanones at 600-630 degrees C produces isomeric gamma,delta-unsaturated cycloalkanones expanded by two carbon atoms. A reaction mechanism involving an open-chain diradical intermediate, followed by intramolecular recombination under insertion of the vinyl group is proposed. Substituents on the vinyl moiety are transferred locospecifically to the ring-expanded ketones as corresponding beta- and gamma-substituents, respectively. The preparation of extraordinary cyclic allenes can be accomplished by DGPTI (540 degrees C) of 3-ethinylcyclododecanone. 相似文献
6.
7.
8.
Beng S. Ong 《Tetrahedron letters》1980,21(44):4225-4228
AlCl3 has been found to be an efficient reagent for promoting thioacetal- and ketalization of carbonyl compounds. 相似文献
9.
Ying-Chih Lin 《中国化学会会志》1985,32(3):295-299
We report the synthesis of metal-metal bonded dinuclear ruthenium ketene complex [CpRu(CO)]2(μ-CH2CO)(μ-CO), 3 , (Cp=η5-C5H5) which contains the unique structural feature, of a μ-η2(C,C) ketene group bridging two metal centers. Complex 3 is prepared by a rare intramolecular CO insertion to the methylene group of a Ru complex [CpRu(CO)2]2(μ-CH2), 1 , in the absence of CO or any donor ligand. The cis and trans isomers of 3 originating from the arrangement of the Cp groups and the unsymmetrically bridging ketene group, are observed in the NMR spectra. Unlike a ketene complex without a metal-metal bond [CpRu(CO)2]2(μ-CH2CO), 2 , complex 3 exhibits the chemistry of a ketene molecule and might be used as a stoichiometric ketene precusor in organic reactions. 相似文献
10.
J. V. Crivello Y.-L. Lai R. Malik 《Journal of polymer science. Part A, Polymer chemistry》1996,34(15):3103-3120
A study of the photoinduced cationic polymerization of a novel series of cyclic and acyclic ketene acetal monomers was carried out. It was observed that the cyclic monomers underwent facile cationic polymerization to give high molecular weight polymers while the acyclic ketene acetals did not. Thermally induced polymerization was also observed on standing catalyzed by glass surfaces. Photoinduced cationic polymerizations employing both diaryliodonium and triarylsulfonium salt photoinitiators were studied. It was observed that the position and type of substitutents in the cyclic ketene acetals was the major factor in determining the proportion of vinyl and ring-opening polymerizations that take place. © 1996 John Wiley & Sons, Inc. 相似文献
11.
12.
J. V. Crivello R. Malik Y.-L. Lai 《Journal of polymer science. Part A, Polymer chemistry》1996,34(15):3091-3102
A new, facile, and high-yield synthesis of ketene acetals derived from readily available and inexpensive starting materials has been developed. For example, an α,β-unsaturated aldehyde can be condensed with an alkane diol to afford a 2-vinyl substituted cyclic acetal. This latter compound can be converted to the desired cyclic ketene acetal by isomerization of the double bond in the presence of tris(triphenylphosphine)ruthenium(II) dichloride. Good to excellent yields of cyclic ketene acetals were obtained employing this method. The novel monomers were fully characterized by IR, NMR, and by elemental analysis. © 1996 John Wiley & Sons, Inc. 相似文献
13.
β-Oxodithioesters are obtained in good yields from acyl ketenedithioacetals on treatment with hydrogen sulphide in the presence of boron trifluoride eiherate in refluxing dioxane 相似文献
14.
A novel and convenient synthesis of ketene acetals 1a-g in moderate to good yield has been achieved starting from acetonitrile by using Pinner reaction approach. 相似文献
15.
The addition of dialkylphosphites to methylvinylketone giving dialkyl‐3‐oxobutylphos‐ phonates was studied applying different reagents, such as NaOR/ROH, NaOH/H2O under PTC, DBU, and R3Al (R = Me, Et) under different conditions to find the optimum choice regarding efficiency and selectivity. Possible extensions to a few other model compounds were also investigated. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:226–229, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20266 相似文献
16.
本文采用酸为催化剂,实施了具有代表性的各种烷硫基α,α-二乙酰基二硫缩烯酮的脱乙酰基反应,得到了一条简洁、通用的α-乙酰基二硫缩烯酮的合成路线.用浓硫酸作催化剂,以极高的产率(90%—100%)制得到相应的α-乙酰基二硫缩烯酮.同时,通过控制反应时间,还可以得到硫代乙酰乙酸酯类化合物. 相似文献
17.
Patrick Hemberger Zeyou Pan Andras Bodi Jeroen A. van Bokhoven Thomas K. Ormond G. Barney Ellison Nadav Genossar Joshua H. Baraban 《Chemphyschem》2020,21(19):2217-2222
Unveiling reaction mechanisms by isomer-selective detection of reactive intermediates requires advanced spectroscopic knowledge. We study the photoionization of fulvenone (c-C5H4=C=O), a reactive ketene species relevant in catalytic pyrolysis of lignin, which was generated by pyrolysis of 2-methoxy acetophenone. The high-resolution threshold photoelectron spectrum (TPES) with vacuum ultraviolet synchrotron radiation revealed well-resolved vibrational transitions, assigned to ring deformation modes of the cyclopentadiene moiety. The adiabatic ionization energy was determined to be 8.25±0.01 eV and is assigned to the 2A2← 1A1 transition. A broad and featureless band arising at 9 eV is associated with the 2B1← 1A1 excitation. A conical intersection is responsible for the ultrafast relaxation of the fulvenone cation from the into the state resulting in a featureless and lifetime broadened band. These insights will increase the detection capabilities for fulvenone and thereby help to elucidate reaction mechanisms in lignin catalytic pyrolysis. 相似文献
18.
19.
D Enders A Greb K Deckers P Selig C Merkens 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(33):10226-10229
Quadruple domino/Wittig-one pot: An organocatalytic, asymmetric, three-component quadruple cascade, which leads to tetracyclic double-annulated indole derivatives, is described. The domino products were further derivatized by aldehyde olefination under one-pot conditions to obtain complex isoindolo[2,?1-a]indole derivatives bearing six stereogenic centers in a highly stereoselective fashion. 相似文献
20.
A variety of functionalised β-iodoacetals have been prepared, and their elimination reaction to give ketene acetals conducted under mild conditions. 相似文献