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221.
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Intermolecular dienyl Pauson-Khand reaction 总被引:1,自引:0,他引:1
Wender PA Deschamps NM Williams TJ 《Angewandte Chemie (International ed. in English)》2004,43(23):3076-3079
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A facile, mild, and efficient methodology for the ionic Diels–Alder reaction of acetals of α,β‐unsaturated ketones and aldehydes as dienophiles with various 1,3‐dienes employing MgBr2 as the Lewis acid catalyst to furnish corresponding Diels–Alder adducts at ambient temperature is described. 相似文献
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E. I. Klimova M. Martinez Garcia T. Klimova L. Ruiz Ramirez N. N. Meleshonkova 《Russian Chemical Bulletin》1999,48(11):2153-2157
3-Cyclobutyl-3-ferrocenylcyclopropene was synthesized by the reactions of mono- or dibromoferrocenylcyclopropanes with ButOK in DMSO. Treatment of dibromoferro-cenylcyclopropane with ButOK in THF afforded 3-cyclobutylidene-3-ferrocenylpropyne in 52% yield. Heterolysis of the C-C bond in the three-membered ring
of 3-cyclobutyl-3-ferrocenylcyclopropene at low and high temperatures was studied. Hydrolysis yielded 3-cyclobutyl-1H-cyclopentaferrocene and products with linear structures,viz., 3-cyclobutylidene-3-ferrocenylpropene,E- andZ-I-ferrocenyl-1-cyclobutylpropenes, and 1-cyclobutylidene-1-ferrocenylacetone. Cyclopropene reacts with 1,3-diphenylisobenzofuran
to form two Diels-Alder adducts, while the enyne does not react with 1,3-diphenylbenzofuran.
Facultad de Quimica, Universidad Nacional Autónoma de México, Cd. Universitaria, C.P. 04510, México D. F., México.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2177–2181, November, 1999. 相似文献
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Eiichi Kobayashi Nahoto Hayashi Sadahito Aoshima Junji Furukawa 《Journal of polymer science. Part A, Polymer chemistry》1998,36(11):1707-1716
It was found that poly(butadiene), poly(isoprene), and poly(2,3-dimethylbutadiene) with high cis-1,4 content were obtained with Nd(OCOR)3–(i-Bu)3Al–Et2AlCl catalysts (R = CF3, CCl3, CHCl2, CH2Cl, CH3) in hexane at 50°C [cis-1,4 content: poly(BD), > 98%; poly(IP), ≥ 96%; poly(DMBD), ≥ 94%]. Copolymerization of IP and styrene (St) was carried out at various monomer feed ratios to evaluate the monomer reactivity ratio and cis-1,4 content of the diene unit and then to elucidate the cis-1,4 polymerization mechanism of IP. The cis-1,4 content of the IP unit in the copolymers decreased with increasing St content in the copolymers. The cis-1,4 polymerization was disturbed by incorporating St unit in the copolymers, since the penultimate St unit hardly coordinates to the neodymium metal, resulting in a decrease of the cis-1,4 content in the copolymers. That is, the cis-1,4 polymerization of IP is suggested to be controlled by a back-biting coordination of the penultimate diene unit. On the other hand, in the case of poly(BD-co-IP) and poly(BD-co-DMBD), the cis-1,4 content of the BD, IP, and DMBD units in the copolymers was almost constant (cis: 94–98%), irrespective of the monomer feed ratios and polymerization temperature. Consequently, the penultimate IP and DMBD units favorably control the terminal BD, IP, or DMBD unit to the cis-1,4 configuration through the back-biting coordination. For the monomer reactivity ratios, a clear difference was observed in each system: rBD = 1.22, rIP = 1.14; rBD = 40.9, rDMBD = 0.15. Low polymerizability of DMBD was mainly ascribed to the steric effect of the methyl substituents. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1707–1716, 1998 相似文献
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《Mendeleev Communications》2023,33(4):479-480
A simple and facile synthesis of racemic 15-deoxy-Δ12,14-prostaglandin J2 methyl ester from readily available Corey lactone diol in total eleven steps was suggested. The standard methods provided a pathway to a block with an integrated w w w-chain and further to PGJ2 methyl ester. The latter was smoothly converted to the target prostaglandin in the TsOH–CH2Cl2 medium when allylic alcohol moiety was transformed to exocyclic diene substituent conjugated with endocyclic enone system. 相似文献