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81.
Tomohiro Hirano Ryoko Takeyoshi Makiko Seno Tsuneyuki Sato 《Journal of polymer science. Part A, Polymer chemistry》2002,40(14):2415-2426
Radical polymerizations of di‐n‐butyl itaconate were investigated. Unexpected resonances (C resonances) were observed in 13C NMR spectra of C?O of poly(di‐n‐butyl itaconate)s [poly(DBI)s] obtained at temperatures higher than 60 °C, although two kinds of carbonyl groups showed splittings due to triad tacticities in the spectra of polymers obtained at lower temperatures. The poly(DBI)s formed by the different kinds of initiators or formed in the presence of chain‐transfer agents showed hardly any changes in the intensities of the C resonances; this indicated that the C resonances were not due to the structures formed through initiating and terminating reactions. The poly(DBI)s obtained at different yields showed only a slight increase in the intensities of the C resonances with the yield, which suggested that the C resonances were not attributable to the intermolecular chain‐transfer reaction to the monomer and/or polymer. However, the intensities of the C resonances significantly increased with a decreasing feed monomer concentration; this suggested that intramolecular chain‐transfer reactions took place at high temperatures. Furthermore, a Cu complex‐catalyzed atom transfer radical polymerization mechanism was revealed to be effective for suppressing the intramolecular chain‐transfer reaction at 60 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2415–2426, 2002 相似文献
82.
[reaction: see text] Oligomerization of Pd(OAc)2(L)2 (L = pyridine derivatives), a catalyst for the air oxidation of alcohols, is studied with MALDI TOF mass, using dithranol as the matrix. The degree of the Pd oligomerization is influenced by the pyridine ligands, and this ligand effect is similar to one observed for Pd black formation in the catalysis. 相似文献
83.
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85.
Tetsuo Iwasawa 《Tetrahedron letters》2008,49(36):5244-5246
A straightforward route to functionalized pentaarylbenzene derivatives is described, involving the effective lithiation method of 1-iodo-2,3,4,5,6-pentaarylbenzene. The activated pentaarylbenzene is a potential synton for producing organic materials. 相似文献
86.
Dr. Naoyuki Toriumi Kazuya Yamashita Prof. Dr. Nobuharu Iwasawa 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(49):12635-12641
A metal-free photoredox-catalyzed hydrodefluorination of fluoroarenes was achieved by using N,N,N’,N’-tetramethyl-para-phenylenediamine ( 1 ) as a strong photoreduction catalyst. This reaction was applicable not only to electron-rich monofluoroarenes but also to polyfluoroarenes to afford non-fluorinated arenes. The experimental mechanistic studies indicated that the amide solvent NMP plays an important role for regeneration of the photocatalyst, enabling additive-free photoreduction catalysis. 相似文献
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We describe a versatile and efficient method for the preparation of acyloxy-substituted six-membered cyclic phosphonates using the ring-closing metathesis. After closure, the key cyclic phosphonate intermediate was dihydroxylated and converted to a new class of conformationally constrained PA and LPA analogues. The oleoyloxy-substituted cyclic phosphonate 4 had unique receptor-selective properties as a ligand, showing partial activation of the LPA2 GPCR and weak antagonism of the LPA1 GPCR. 相似文献
89.
Kita Y Matsuda S Inoguchi R Ganesh JK Fujioka H 《The Journal of organic chemistry》2006,71(14):5191-5197
The Lewis acid-promoted rearrangement of 2,2,3,3-tetrasubstituted 2,3-epoxy alcohols with several kinds of protecting groups was investigated. When SnCl4 is used as a Lewis acid, the reaction proceeds in a regio- and stereo-controlled manner to afford two types of carbonyl compounds selectively from a single 2,3-epoxy alcohol only by changing the protecting group of the alcohol. The method was then applied to the formation of two types of acyclic and cyclic quaternary carbon centers from the single compound in optically active forms. 相似文献
90.
[reaction: see text] A concise method for the preparation of isochromene carboxylates has been developed by the regioselective 1,6-addition of various nucleophiles such as Grignard reagents, alkoxide, and cyanide onto benzopyranylidenetungsten(0) complexes, followed by iodine oxidation of the addition intermediates. 相似文献