- Gold(I)-Catalyzed Oxidative 1,4-Additions of 3-En-1-ynamide with Nitrones via Carbon- versus Nitrogen-Addition Chemoselectivity
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This work reports gold-catalyzed 1,4-oxofunctionalizations of 3-en-1-ynamides with nitrones, yielding two distinct E-configured products. We obtained 1,4-oxoarylation products from 3-en-1-ynamides bearing C(4)-electron-donating substituents and 1,4-oxoamination products from those analogues bearing C(4)-aryl substituents. We propose that if vinylgold carbenes are stable, imines undergo a para-arylation on these gold carbenes. If vinylgold carbenes are highly electron-deficient, this N-attack is irreversible to enable 1,4-oxoaminations.
- Tanpure, Sudhakar Dattatray,Kale, Balaji S.,Liu, Rai-Shung
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supporting information
p. 1394 - 1399
(2021/02/20)
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- Metal-free cascade boron–heteroatom addition and alkylation with diazo compounds
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Transition metal-catalyzed carbene transfer reaction is one of the most notable advances for C?C bond formation reactionsduring the past decade, which has been widely employed in the preparation of C3-substituted indoles. Here, we described an efficient e
- Lv, Jiahang,Zhao, Binlin,Han, Ying,Yuan, Yu,Shi, Zhuangzhi
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p. 691 - 694
(2020/07/13)
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- A facile asymmetric approach to the multicyclic core structure of mangicol A
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Chiral propargylic ether-based triene-ynes are synthesized with high enantiomeric purity by employing an asymmetric enyne addition to aldehydes catalyzed by 1,1′-bi-2-naphthol in combination with ZnEt2, Ti(OiPr)4 and dicy-clohexylami
- Ying, Jun,Pu, Lin
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p. 16301 - 16307
(2015/01/08)
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- Isomerization of propargylic alcohols into α,β-unsaturated carbonyl compounds catalyzed by the sixteen-electron allyl-ruthenium(II) complex [Ru(η3-2-C3H4Me)(CO)(dppf)] [SbF 6]
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The 16-e- (η3-allyl)-ruthenium(II) complex [Ru(η3-2-C3H4Me)(CO)(dppf)][SbF 6] is an efficient catalyst for the regioselective isomerization of terminal propargylic alcohols HC≡CCR1R2(OH) into α,β-unsaturated aldehydes R1R2C=CHCHO or ketones R3R4C=C(R1)COMe (if R2 = CHR3R4) under mild conditions. This complex has been also used as catalyst for the preparation of conjugated 1,3-enynes via dehydration of propargylic alcohols.
- Cadierno, Victorio,Garcia-Garrido, Sergio E.,Gimeno, Jose
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p. 101 - 110
(2007/10/03)
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- Ruthenium-catalyzed propargylic substitution reactions of propargylic alcohols with oxygen-, nitrogen-, and phosphorus-centered nucleophiles
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The scope and limitations of the ruthenium-catalyzed propargylic substitution reaction of propargylic alcohols with heteroatom-centered nucleophiles are presented. Oxygen-, nitrogen-, and phosphorus-centered nucleophiles such as alcohols, amines, amides, and phosphine oxide are available for this catalytic reaction. Only the thiolate-bridged diruthenium complexes can work as catalysts for this reaction. Results of some stoichiometric and catalytic reactions indicate that the catalytic propargylic substitution reaction proceeds via an allenylidene complex formed in situ, whereby the attack of nucleophiles to the allenylidene Cγ atom is a key step. Investigation of the relative rate constants for the reaction of propargylic alcohols with several para-substituted anilines reveals that the attack of anilines on the allenylidene Cγ atom is not involved in the rate-determining step and rather the acidity of conjugated anilines of an alkynyl complex, which is formed after the attack of aniline on the C γ atom, is considered to be the most important factor to determine the rate of this catalytic reaction. The key point to promote this catalytic reaction by using the thiolate-bridged diruthenium complexes is considered to be the ease of the ligand exchange step between a vinylidene ligand on the diruthenium complexes and another propargylic alcohol in the catalytic cycle. The reason why only the thiolate-bridged diruthenium complexes promote the ligand exchange step more easily with respect to other monoruthenium complexes in this catalytic reaction should be that one Ru moiety, which is not involved in the allenylidene formation, works as an electron pool or a mobile ligand to another Ru site. The catalytic procedure presented here provides a versatile, direct, and one-step method for propargylic substitution of propargylic alcohols in contrast to the so far well-known stoichiometric and stepwise Nicholas reaction.
- Nishibayashi, Yoshiaki,Milton, Marilyn Daisy,Inada, Youichi,Yoshikawa, Masato,Wakiji, Issei,Hidai, Masanobu,Uemura, Sakae
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p. 1433 - 1451
(2007/10/03)
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- Chemistry and structure-activity relationships of C-17 unsaturated 18-cycloalkyl and cycloalkyl analogues of enisoprost. Identification of a promising new antiulcer prostaglandin
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A series of Δ17 unsaturated cycloalkyl and cycloalkenyl analogues of enisoprost was synthetized to investigate the effects of ω chain unsaturation on gastric antisecretory activity and diarrheogenic side effects. Of these, the 17E, 18-cyclopent
- Collins,Gasiecki,Perkins,Gullikson,Bianchi,Kramer,Ng,Yonan,Swenton,Jones,Bauer
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p. 2784 - 2793
(2007/10/02)
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