- Cyclobutene vs 1,3-Diene Formation in the Gold-Catalyzed Reaction of Alkynes with Alkenes: The Complete Mechanistic Picture
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The intermolecular gold(I)-catalyzed reaction between arylalkynes and alkenes leads to cyclobutenes by a [2 + 2] cycloaddition, which takes place stepwise, first by formation of cyclopropyl gold(I) carbenes, followed by a ring expansion. However, 1,3-butadienes are also formed in the case of ortho-substituted arylalkynes by a metathesis-type process. The corresponding reaction of alkenes with aryl-1,3-butadiynes, ethynylogous to arylalkynes, leads exclusively to cyclobutenes. A comprehensive mechanism for the gold(I)-catalyzed reaction of alkynes with alkenes is proposed on the basis of density functional theory calculations, which shows that the two pathways leading to cyclobutenes or dienes are very close in energy. The key intermediates are cyclopropyl gold(I) carbenes, which have been independently generated by retro-Buchner reaction from stereodefined 1a,7b-dihydro-1H-cyclopropa[a]naphthalenes.
- De Orbe, M. Elena,Amenós, Laura,Kirillova, Mariia S.,Wang, Yahui,López-Carrillo, Verónica,Maseras, Feliu,Echavarren, Antonio M.
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p. 10302 - 10311
(2017/08/09)
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- Zinc-mediated enantioselective addition of terminal 1,3-diynes to N-arylimines of trifluoropyruvates
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A facile and effective enantioselective addition of terminal 1,3-diynes to acyclic α-CF3 ketimine esters has been developed by using zinc/Binol complexes. The reaction works well with a variety of aromatic-, aliphatic- and silyl-substituted diynes, providing the desired products in up to 97% yield and 97% enantiomeric excess.
- Zhang, Fa-Guang,Ma, Hai,Zheng, Yan,Ma, Jun-An
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scheme or table
p. 7663 - 7669
(2012/09/05)
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- Synthesis, structures and reactions of isolable terminal aryl/biarylbutadiynes (Ar-C≡C-C≡CH)
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The synthesis and isolation is reported of five terminal aryl/biaryl-butadiynes, Ar-C≡C-C≡CH, (5a-c, 10a and 10b) from 2-methyl-6-aryl/biaryl-hexa-3,5-diyn-2-ol precursors [Ar-C≡C-C≡C- C(Me)2OH; Ar = 2-MeOC6H4, 3-MeOC sub
- West, Kara,Hayward, Laura N.,Batsanov, Andrei S.,Bryce, Martin R.
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supporting information; experimental part
p. 5093 - 5098
(2009/05/26)
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- Polydiphenyldiacetylenes
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Disclosed herein are polydiphenyldiacetylenes having the following repeating unit (III): STR1 (wherein R1 denotes a hydrogen atom or a methoxy group; R2 denotes a hydrogen atom, a methoxy group or a methylamino group; R3 d
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- PREPARATION AND NONLINEAR OPTICAL PROPERTY OF POLYDIACETYLENES FROM UNSYMMETRICAL DIPHENYLBUTADIYNES WITH TRIFLUOROMETHYL SUBSTITUENTS
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In order to obtain the polydiacetylenes having ?-conjugation between polymer backbone and side chains, many of unsymmetrical diphenylbutadiyne derivatives with trifluoromethyl substituents on one of the phenyl rings have been synthesized.Among them, 1-(3-(methylamino)phenyl)-4-(3,5-bis(trifluoromethyl)phenyl)butadiyne (MADF) was found to be topochemically polymerized with complete conversion into the polymer single crystals.Spectroscopies and X-ray crystal structure analysis revealed that the ?-conjugation of this polymer are more extended than those of the sofar prepared poly(diphenylbutadiyne)s, with smaller dihedral angles between ?-conjugation planes of polymer backbone and phenyl rings.The extended ?-conjugation was also confirmed by larger χ(3) values.
- Okada, Shuji,Ohsugi, Minoru,Masaki, Atsushi,Matsuda, Hiro,Takaragi, Shigeru,Nakanishi, Hachiro
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