7564-63-8Relevant academic research and scientific papers
Pd-Catalyzed Synthesis of Vinyl Arenes from Aryl Halides and Acrylic Acid
Gao, Yang,Ou, Yang,Goo?en, Lukas J.
supporting information, p. 8709 - 8712 (2019/06/17)
Acrylic acid is presented as an inexpensive, non-volatile vinylating agent in a palladium-catalyzed decarboxylative vinylation of aryl halides. The reaction proceeds through a Heck reaction of acrylic acid, immediately followed by protodecarboxylation of the cinnamic acid intermediate. The use of the carboxylate group as a deciduous directing group ensures high selectivity for monoarylated products. The vinylation process is generally applicable to diversely substituted substrates. Its utility is shown by the synthesis of drug-like molecules and the gram-scale preparation of key intermediates in drug synthesis.
Process for synthesizing 2-ethyl styrene
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Paragraph 0023; 0026; 0027; 0028; 0031; 0032; 0033; 0036, (2018/07/06)
The invention discloses a process for synthesizing 2-ethyl styrene. The process comprises the following specific steps of: (1) dissolving 2-ethyl bromobenzene in a dry polar organic solvent, adding n-butyl lithium dropwise at a low temperature for 1-4 hours, maintaining the temperature for a reaction at the low temperature for 1-6 hours after addition is completed dropwise, then adding anhydrous N,N-dimethylformamide, maintaining the temperature for 1-6 hours after addition is completed, adding a quenching solvent for quenching, performing washing by using water, keeping the obtained mixture standing for stratification, concentrating an organic phase without additional purification so as to obtain an intermediate with a yield of 95-100%; and (2) mixing the intermediate, an inorganic base,triphenyl methyl phosphine and the dry solvent, maintaining the temperature for a reaction for 2-10 hours under an inert atmosphere and a reflux condition after mixing is completed, and performing post-treatment to obtain the pure target product with a yield of 80-90%. The product produced by the process has the advantages of good quality, stable operation, high yield, less three-waste and low production cost.
Vinylation of aryl bromides using an inexpensive vinylpolysiloxane
Denmark, Scott E.,Butler, Christopher R.
, p. 63 - 66 (2007/10/03)
(Chemical Equation Presented) A mild and general method for the palladium-catalyzed vinylation of aryl bromides has been developed. The use of tetrabutylammonium fluoride (TBAF) as the activator and an inexpensive and nontoxic vinyl donor, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4V, 1), allows for a general and high-yielding preparation of substituted styrenes.
Polymeric nitrons. 2. Synthesis, irradiation and waveguide mode spectroscopy of polymeric nitrons derived from polymeric benzaldehydes and N-isopropylhydroxylamine
Heinenberg, Michael,Menges, Bernhard,Mittler, Silvia,Ritter, Helmut
, p. 3448 - 3455 (2007/10/03)
Various vinylbenzaldehydes were prepared using the Heck reaction: 4-vinylbenzaldehyde (14), 3-vinylbenzaldehyde (15), 2-vinylbenzaldehyde (18a), 2-hydroxy-4-vinylbenzaldehyde (16) and 4-[(4-vinylbenzyl)oxy]benzaldehyde (6). The four monomers (6, 14, 15, 16) were polymerized using AIBN as initiator at 70 °C for 24 h to yield the corresponding homopolymers (7, 19, 23, 25) and a copolymer (20) with styrene. The molecular weights are about 10 000. The polymer analogous condensation of the aldehyde groups with an excess of N-isopropylhydroxylamine (8) at room temperature produces polymeric nitrons (9, 21, 22, 24, 26) in almost quantitative yields. All nitron functions were irradiated, and the intramolecular cyclization of the nitrons to the corresponding oxaziridines was examined. Waveguide mode spectroscopy of poly(4-vinylbenzaldehyde-N-isopropylnitron) (21) shows that the changes in film thickness are low but the changes in refractive indices are significant after irradiation. Oxaziridine 10 has high thermal stability with respect to ring opening. No structural change was detected after irradiation of the hydrexyphenyl-modified polynitron (26). A low molecular weight model compound (2-hydroxybenzaldehyde-N-methylnitron, 28) was prepared id order to examine this abnormal photochemical behavior and also showed that it is highly resistant to UV irradiation.
Forbidden reactions, II. - The disrotatory cyclobutene ringopening
Roth, Wolfgang R.,Rekowski, Volker,Boerner, Sabine,Quast, Michael
, p. 409 - 430 (2007/10/03)
The energy profiles for the con- and disrotatory opening of benzocyclobutene, methylenecyclobutene, and cyclobutene derivatives were established by NO and oxygen trapping. The enthalpy for the transition states for the "forbidden" reactions proofed to be identical with the heat of formation of the orthogonal diradicals derived by geometrical isomerization of the dienes formed in these reactions. These diradicals describe very well the activation barriers observed for the disrotatory opening of bicyclic cyclobutenes ([3.2.0] and [2.2.0] systems), but not for bicyclo[2.1.0]pent-2-ene, indicating here a truly forbidden reaction. VCH Verlagsgesellschaft mbH, 1996.
Photolysis and Flash Thermolysis of some 1,3-Dihydrobenzothiophen 2,2-Dioxides
Durst, Tony,Lancaster, Michael,Smith, David J. H.
, p. 1846 - 1848 (2007/10/02)
The thermolysis and photolysis of the title compounds (7) have been studied.Benzocyclobutenes (8) are the major products at lower temperatures whereas alkenes (9), derived from a hydride shift, predominante at higher temperatures and on photolysis.
Kinetic Evidence for the Formation of Discrete 1,4-Dehydrobenzene Intermediates. Trapping by Inter- and Intramolecular Hydrogen Atom Transfer and Observation of High-Temperature CIDNP
Lockhart, Thomas P.,Comita, Paul B.,Bergman, Robert G.
, p. 4082 - 4090 (2007/10/02)
Upon being heated, alkyl-substituted cis-1,2-diethynyl olefins undergo cyclization to yield reactive 1,4-dehydrobenzenes; the products isolated may be derived from either unimolecular or bimolecular reactions of the intermediate. (Z)-4,5-Diethynyl-4-octene (4) undergoes rearrangement to yield 2,3-di-n-propyl-1,4-dehydrobenzene (17).Solution pyrolysis of 4 in inert aromatic solvent produces three unimolecular products, (Z)-dodeca-4,8-diyn-6-ene (7), benzocyclooctene (9), and o-allyl-n-propylbenzene (10), in high yield.When 1,4-cyclohexadiene is added to the pyrolysis solution as a trapping agent, high yields of the reduced product o-di-n-propylbenzene (12) are obtained.The kinetics of solution pyrolysis of 4 in the presence and absence of trapping agent establish that 2,3-di-n-propyl-1,4-dehydrobenzene is a discrete intermediate on the pathway leading to products.When the reaction was run in the heated probe of an NMR spectrometer, CIDNP was observed in 10.This observation, along with kinetic and chemical trapping evidence, indicates the presence of two additional intermediates, formed from 17 by squential intramolecular hydrogen transfer, on the pathway to products.The observation of CIDNP, coupled with the reactivity exhibited by 17 and the other two intermediates, implicates a biradical description of these molecules.Biradical 17 has been estimated to have a lifetime of about 10-9 s at 200 deg C and to lie in a well of about 5 kcal per mole with respect to the lowest energy unimolecular pathway ( hydrogen transfer).Ring opening (expected to be the lowest energy process for 1,4-dehydrobenzenes in which intramolecular hydrogen transfer is unlikely) to the isomeric diethynyl olefin 7 appears to have an activation enthalpy of about 10 kcal/mol.Upon thermal reaction in the gas phase (400 deg C) or in solution in inert solvents (Z)-2,3-diethylhexa-1,5-diyn-3-ene (5) rearranges in good yield to the isomeric diethynyl olefin (Z)-deca-3,7-diyn-5-ene (8) again presumably via 2,3-diethyl-1,4-dihydrobenzene 20 (addition of 1,4-cyclohexadiene to the reaction solution leads to a good yield of o-diethylbenzene, the expected trapping product of biradical 20).The absence of products due to intramolecular hydrogen transfer indicates that this process is at least 1 or 2 orders of magnitude slower than hydrogen transfer in 17.At 500 deg C in the gas phase products due to hydrogen transfer begin to appear.
