共查询到20条相似文献,搜索用时 15 毫秒
1.
Madison J. Sowden Jas S. Ward Michael S. Sherburn 《Angewandte Chemie (International ed. in English)》2020,59(10):4145-4153
The first general preparative access to compounds of the 2,3‐diethynyl‐1,3‐butadiene (DEBD) class is reported. The synthesis involves a one‐pot, twofold Sonogashira‐type, Pd0‐catalyzed coupling of two terminal alkynes and a carbonate derivative of a 2‐butyne‐1,4‐diol. The synthesis is broad in scope and members of this structural family are kinetically stable enough to be handled using standard laboratory techniques at ambient temperature. They decompose primarily through heat‐promoted cyclodimerizations, which are impeded by alkyl substitution and accelerated by aryl or alkenyl substitution. An iterative sequence of these unprecedented Sonogashira‐type couplings generates a new type of expanded dendralene. A suitably substituted DEBD carrying two terminal alkyne groups undergoes Glaser–Eglinton cyclo‐oligomerization to produce a new class of expanded radialenes, which are chiral due to restricted rotation about their 1,3‐butadiene units. The structural features giving rise to atropisomerism in these compounds are distinct from those reported previously. 相似文献
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Michael I. Bruce Nicholas J. Head Brian W. Skelton Allan H. White 《Acta Crystallographica. Section C, Structural Chemistry》2004,60(1):o60-o61
The principal determinants of packing in crystals of the title compound, C12H10O2, which has crystallographically imposed inversion symmetry, are interactions between the alkyne H atoms and the methoxy O atoms [H⋯O = 2.39 (1) Å]. 相似文献
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Shaobin Miao Dr. Anthony L. Appleton Nancy Berger Stephen Barlow Dr. Seth R. Marder Prof. Kenneth I. Hardcastle Dr. Uwe H. F. Bunz Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(20):4990-4993
A new relative of pentacene : The dialkynylated tetraazapentacene (see figure) was prepared by a two‐step synthesis from the corresponding quinone derivative. The heteroacene is an air‐stable, dark‐blue, crystalline material and is of great interest as a potential organic n‐electron‐transport material.
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Michael Z. Liang Simon J. Meek 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(40):14372-14377
A catalytic enantioselective method for the synthesis of 1,4‐keto‐alkenylboronate esters by a rhodium‐catalyzed conjugate addition pathway is disclosed. A variety of novel, bench‐stable alkenyl gem‐diboronate esters are synthesized. These easily accessible reagents react smoothly with a collection of cyclic α,β‐unsaturated ketones, generating a new C?C bond and stereocenter. Products are isolated in up to 99 % yield with greater than 20:1 E/Z and greater than 99:1 e.r. Mechanistic studies show the site‐selectivity of transmetalation and reactivity is ligand dependent. The utility of the approach is highlighted by gram‐scale synthesis of enantioenriched cyclic 1,4‐diketones, and stereoselective transformations of the products by hydrogenation, allylation, and isomerization. 相似文献
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Scope and limitations of 1,4‐anhydro sugars as precursors of glycofuranosyl building blocks are described. The experiments revealed that the choice of the substituents is very important for an efficient preparation as well as a successful ring‐opening reaction of 1,4‐anhydro sugars. DFT Calculations suggest that selective protonation of 1,4‐anhydro sugars is the key to the selective ring opening in order to afford only furanosides. 相似文献
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Philip Dimitrov Pradeep Iyer Marcel Van Beylen Thieo E. Hogen‐Esch 《Journal of polymer science. Part A, Polymer chemistry》2009,47(8):2198-2206
The anionic polymerization of butadiene initiated with 1,4‐dilithio‐1,1,4,4‐tetraphenylbutane (LiTPB) in diethyl ether (DEE) gives polybutadiene (PBD) with high 1,2 content (>70%), narrow polydispersities (1.04 < Mw/Mn < 1.20), and predicted molecular weights. In THF, this polymerization does not work very well. After removal of DEE and addition of THF, the PBD dianion is end capped quantitatively by addition of 1,1‐diphenylethylene (DPE) to give the diphenylalkyl end capped PBD dianion. Subsequent addition of methyl methacrylate at low temperatures results in the formation of well‐defined PMMA‐b‐PBD‐b‐PMMA triblock copolymers. The results are accounted for by taking into account the effects of Li ion solvation on the BD initiation and end capping of the PBD anion by DPE. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2198–2206, 2009 相似文献
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Sven Boomgaarden Wolfgang Saak Heinrich Marsmann Manfred Weidenbruch 《无机化学与普通化学杂志》2001,627(5):805-806
The reaction of hexakis(2,4,6‐triisopropylphenyl)tetrasilabuta‐1,3‐diene with anhydrous hydrazine furnishes the correspondingly substituted 1,4‐dihydrazinotetrasilane 2 . The X‐ray structure analysis of 2 reveals that the compound crystallizes as a conglomerate of enantiomerically pure crystals. 相似文献
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Astrid Lumetzberger Werner Löwe Manuela Weber Peter Luger 《Journal of heterocyclic chemistry》2007,44(1):155-159
The (Z)‐3‐substituted 2‐indolinone 6 was prepared using the aldehydes 4 and 8 unknown up to now and 2‐indolinone. 相似文献
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Andrés E. Ciolino Marcelo A. Villar Enrique M. Vallés Nikos Hadjichristidis 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2726-2733
Model copolymers of poly(butadiene) (PB) and poly(dimethylsiloxane) (PDMS), PB‐b‐PDMS‐b‐PB, were synthesized by sequential anionic polymerization (high vacuum techniques) of 1,3‐butadiene and hexamethylciclotrisiloxane (D3) on sec‐BuLi followed by chlorosilane‐coupling chemistry. The synthesized copolymers were characterized by nuclear magnetic resonance (1H NMR), size‐exclusion chromatography (SEC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). SEC and 1H NMR results showed low polydispersity indexes (Mw/Mn) and variable siloxane compositions, whereas DSC and TGA experiments indicated that the thermal stability of the triblock copolymers depends on the PDMS composition. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2726–2733, 2007 相似文献
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Yasuhiro Tanoue Moritsugu Hamada Norihisa Kai Kazunori Sakata Mamoru Hashimoto Takeshi Nagai 《Journal of heterocyclic chemistry》2005,42(6):1195-1199
The usefulness of 3‐iodoindoles available for introduction of an indole unit is presented. The reaction of various halo‐3‐iodoindoles with 1,4‐naphthoquinone gave the corresponding 2‐(3‐indolyl)‐1‐4,naphthoquinones in moderate yields. The 3‐iodoindole was used for synthesis of a compound containing both naph‐thazarin and indole skeletons. 相似文献
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Jing‐Yu He Xiu‐Qing Song Hong Yan Ru‐Gang Zhong 《Journal of heterocyclic chemistry》2012,49(6):1357-1361
The 4‐aryl‐1,4‐dihydropyrazines were prepared via the cyclization of N,N‐bisalkylated anilines with ammonium acetate. These reactions were aided by improvements in the synthesis of N,N‐bisalkylated anilines which were alkylated with anilines using ethyl 2‐diazo acetoacetate in a reaction catalyzed by rhodium acetate in the absence of oxygen. A possible mechanistic route is postulated on the basis of the isolation of the N‐alkylation intermediates, which were determined to be N‐aryloxamates by 1H NMR data and X‐ray diffraction. 相似文献
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Louis Pergaud Sandjo Victor Kuete Frederic Nana Gilbert Kirsch Thomas Efferth 《Helvetica chimica acta》2016,99(4):310-314
Eight heterocycles have been prepared in a one‐pot reaction manner based on the Hantzsch dihydropyridine synthesis. The synthesis afforded seven dihydropyridines (DHP) and one unexpected 1,3‐oxazin‐6‐one. Their structures were confirmed based on NMR spectroscopy and mass spectrometry. The obtained products have been evaluated for their cytotoxicity against eight cancer cell lines and one normal cell line. Two halogenated DHPs ( 7 and 8 ) displayed cytotoxicity toward all the nine tested cancer cell lines with IC50 values from 4.10 to 58.90 μm, while others showed selective activities. DHPs ( 7 and 8 ) bearing a Me group at C(2) and C(6) as well as a halogenated substituent at C(4′) were more antiproliferative than the others. 相似文献
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Aurora Molinari Alfonso Oliva Marlene Arismendi Elizabeth Imbarack Cristian Glvez Javier Maldonado Arturo San Feliciano 《Journal of heterocyclic chemistry》2015,52(2):620-622
New fused pyrazolo‐1,4‐naphthoquinones were prepared from the reaction of hydrazines with 6‐(4‐methyl‐3‐pentenyl)‐1,4‐naphthoquinone. The reaction was extended to hydroxylamine to afford the corresponding isoxazolo‐1,4‐napthoquinone compound. 相似文献
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Synthesis of 1,4‐Cyclohexanedimethanol, 1,4‐Cyclohexanedicarboxylic Acid and 1,2‐Cyclohexanedicarboxylates from Formaldehyde,Crotonaldehyde and Acrylate/Fumarate 下载免费PDF全文
Dr. Yancheng Hu Zhitong Zhao Dr. Yanting Liu Prof. Guangyi Li Prof. Aiqin Wang Prof. Yu Cong Prof. Tao Zhang Prof. Feng Wang Prof. Ning Li 《Angewandte Chemie (International ed. in English)》2018,57(23):6901-6905
Valuable polyester monomers and plasticizers—1,4‐cyclohexanedimethanol (CHDM), 1,4‐cyclohexanedicarboxylic acid (CHDA), and 1,2‐cyclohexanedicarboxylates—have been prepared by a new strategy. The synthetic processes involve a proline‐catalyzed formal [3+1+2] cycloaddition of formaldehyde, crotonaldehyde, and acrylate (or fumarate). CHDM is produced after a subsequent hydrogenation step over a commercially available Cu/Zn/Al catalyst and a one‐pot hydrogenation/oxidation/hydrolysis process yields CHDA, whereas 1,2‐cyclohexanedicarboxylate is obtained by a Pd/C‐catalyzed tandem decarbonylation/hydrogenation step. 相似文献
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《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2018,130(23):7017-7021
Valuable polyester monomers and plasticizers—1,4‐cyclohexanedimethanol (CHDM), 1,4‐cyclohexanedicarboxylic acid (CHDA), and 1,2‐cyclohexanedicarboxylates—have been prepared by a new strategy. The synthetic processes involve a proline‐catalyzed formal [3+1+2] cycloaddition of formaldehyde, crotonaldehyde, and acrylate (or fumarate). CHDM is produced after a subsequent hydrogenation step over a commercially available Cu/Zn/Al catalyst and a one‐pot hydrogenation/oxidation/hydrolysis process yields CHDA, whereas 1,2‐cyclohexanedicarboxylate is obtained by a Pd/C‐catalyzed tandem decarbonylation/hydrogenation step. 相似文献
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Ren T. Boer Christopher O. Bender 《Acta Crystallographica. Section C, Structural Chemistry》2013,69(3):247-250
(1RS,3RS,4RS,10SR)‐2,2,3,10‐Tetrabromo‐1,2,3,4‐tetrahydro‐1,4‐ethanonaphthalene, C12H10Br4, (I), is the first structure to be reported with four Br atoms bound to a 1,4‐ethanonaphthalene framework and also the first which possesses three Br atoms in exo positions. Interactions between the Br atoms [three short intramolecular Br...Br distances of 3.1094 (4), 3.2669 (4) and 3.4415 (5) Å] have little effect on the C—C bond lengths but lead to significant twisting of the cage structure compared with the parent hydrocarbon, which is expected to be fully eclipsed at the two saturated C2H4 bridge positions. Chemically related (1SR,4RS)‐2,3‐dibromo‐1,4‐ethenonaphthalene, C12H8Br2, (II), obtained by double dehydrobromination of (I), represents the first structure of any halogen‐substituted benzobarrelene. This cis‐dibromide shows little evidence of steric congestion at the double bond [Br...Br = 3.5276 (8) Å] as a consequence of the large C—C—Br angles [average C=C—Br angle = 126.15 (10)°]. 相似文献