- Lewis Base/Br?nsted Acid Co-Catalyzed Asymmetric Thiolation of Alkenes with Acid-Controlled Divergent Regioselectivity
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A divergent strategy for the facile preparation of various enantioenriched phenylthio-substituted lactones was developed based on Lewis base/Br?nsted acid co-catalyzed thiolation of homoallylic acids. The acid-controlled regiodivergent cyclization (6-endo vs. 5-exo) and acid-mediated stereoselective rearrangement of phenylthio-substituted lactones were explored. Experimental and computational studies were performed to clarify the origins of the regioselectivity and enantioselectivity. The calculation results suggest that C?O and C?S bond formation might occur simultaneously, without formation of a commonly supposed catalyst-coordinated thiiranium ion intermediate and the potential π–π stacking between substrate and SPh as an important factor in the enantio-determining step. Finally, this methodology was applied in the rapid syntheses of the bioactive natural products (+)-ricciocarpin A and (R)-dodecan-4-olide.
- Luo, Hui-Yun,Dong, Jia-Wei,Xie, Yu-Yang,Song, Xu-Feng,Zhu, Deng,Ding, Tongmei,Liu, Yuanyuan,Chen, Zhi-Min
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- Au-Catalyzed Synthesis of Thiopyrano[2,3-b]indoles Featuring Tandem Rearrangement and Hydroarylation
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Gold(III)-catalyzed synthesis of 14-π electron heteroaromatic thiopyrano[2,3-b]indole is reported using conjugated enyne tethered indole sulfides, featuring skeletal rearrangement conjoined with intramolecular hydroarylation (via C3-H functionalization of the indole core) and oxidative aromatization. Subsequent Pd-catalyzed C-C coupling resulted in a 16-π electron heteroaromatic isothiochromeno[1,8,7-bcd]indole.
- Jha, Mukund,Dhiman, Shiv,Cameron, T. Stanley,Kumar, Dalip,Kumar, Anil
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- Flexible Construction of Functionalized-Pyrroles under Palladium or Copper Catalysis in the Presence of BF3 ? Et2O
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We have developed a flexible approach enabling the access to highly functionalized pyrroles under palladium or copper catalysis in the presence of BF3 ? Et2O. This catalytic methodology utilizes commercially available amines as react
- Liu, Yin,Liu, Teng,Yan, Biwei,Wei, Kun,Guo, Wusheng
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p. 916 - 921
(2022/01/26)
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- Enantio- and Diastereodivergent Synthesis of Spirocycles through Dual-Metal-Catalyzed [3+2] Annulation of 2-Vinyloxiranes with Nucleophilic Dipoles
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The development of efficient and straightforward methods for obtaining all optically active isomers of structurally rigid spirocycles from readily available starting materials is of great value in drug discovery and chiral ligand development. However, the
- Huo, Xiaohong,Luo, Yicong,Peng, Youbin,Wu, Liang,Zhang, Wanbin
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supporting information
p. 24941 - 24949
(2021/10/25)
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- Gold-Catalyzed Asymmetric Thioallylation of Propiolates via Charge-Induced Thio-Claisen Rearrangement
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A gold(I)-catalyzed enantioselective thioallylation of propiolates with allyl sulfides is described. The key mechanistic element is a sulfonium-induced Claisen rearrangement which helps minimize the allyl dissociation and render higher enantioselectivity. This protocol features remarkable scope of the allyl moiety, allowing enantiocontrolled synthesis of all-carbon quaternary centers, and exhibits exceptional functional group compatibility with many Lewis bases and π-bonds. This intermolecular variant of Claisen rearrangement forges both C-S and C-C bonds concomitantly, providing efficient access to interesting optically active organosulfur compounds which can be transformed further through the vinyl sulfide as a functional handle. The rate of the reaction was zeroth order with respect to allyl sulfides, which suggested a reversible inhibition, providing a resting state for the catalyst. The Hammett plot displayed a correlation with σp values, suggesting a turnover-limiting sigmatropic rearrangement where decreased electron-density on sulfur accelerated the rearrangement.
- Kim, Hanbyul,Jang, Jiwon,Shin, Seunghoon
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supporting information
p. 20788 - 20795
(2020/11/27)
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- Auto-Tandem Cooperative Catalysis Using Phosphine/Palladium: Reaction of Morita–Baylis–Hillman Carbonates and Allylic Alcohols
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Auto-tandem catalysis (ATC), in which a single catalyst promotes two or more mechanistically different reactions in a cascade pattern, provides a powerful strategy to prepare complex products from simple starting materials. Reported here is an unprecedented auto-tandem cooperative catalysis (ATCC) for Morita–Baylis–Hillman carbonates from isatins and allylic carbonates using a simple Pd(PPh3)4 precursor. Dissociated phosphine generates phosphorus ylides and the Pd leads to π-allylpalladium complexes, and they undergo a γ-regioselective allylic–allylic alkylation reaction. Importantly, a cascade intramolecular Heck-type coupling proceeds to finally furnish spirooxindoles incorporating a 4-methylene-2-cyclopentene motif. Experimental results indicate that both Pd and phosphine play crucial roles in the catalytic Heck reaction. In addition, the asymmetric versions with either a chiral phosphine or chiral auxiliary are explored, and moderate results are obtained.
- Chen, Peng,Chen, Zhi-Chao,Li, Yue,Ouyang, Qin,Du, Wei,Chen, Ying-Chun
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supporting information
p. 4036 - 4040
(2019/02/24)
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- Manganese-Catalyzed Ring-Opening Coupling Reactions of Cyclopropanols with Enones
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A manganese-catalyzed ring-opening coupling reaction of cyclopropanols with enones for the facile and efficient preparation of 1,6-diketones is described. A wide array of synthetically important 1,6-diketones bearing manifold functional groups are obtained with up to 93% yield. These reactions feature broad substrate scopes, environmentally benign conditions, inexpensive catalyst, and operational simplicity.
- Zhang, Yong-Hui,Zhang, Wen-Wei,Zhang, Ze-Yu,Zhao, Kai,Loh, Teck-Peng
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supporting information
p. 5101 - 5105
(2019/07/03)
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- Double gold-catalysed annulation of indoles by enynones
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The gold-catalysed double functionalisation of indoles is presented. Enynones are used to annulate indoles via a double sodium tetrachloroaurate- catalysed process involving a mixture of C-H activation and alkyne activation modes of promotion. Good yields
- Heffernan, Stephen J.,Tellam, James P.,Queru, Marine E.,Silvanus, Andrew C.,Benito, David,Mahon, Mary F.,Hennessy, Alan J.,Andrews, Benjamin I.,Carbery, David R.
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supporting information
p. 1149 - 1159
(2013/05/22)
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- Synthesis of phosphine-ligated zinc acetylide dimers: Enhanced reactivity in carbonyl additions
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Phosphine-ligated dinuclear zinc acetylides effectively promote the alkynylation of carbonyl derivatives. Good to excellent yields (46-91%) of the corresponding propargylic alcohols were obtained from a wide range of substrates. Crystallographic evidence
- Wilson, Erin E.,Oliver, Allen G.,Hughes, Russell P.,Ashfeld, Brandon L.
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experimental part
p. 5214 - 5221
(2011/11/13)
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- Chiral macrocycle-catalyzed highly enantioselective phenylacetylene addition to aliphatic and vinyl aldehydes
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(Chemical Equation Presented) The 1,1′-binaphthyl macrocycle (S)-2 is found to be an excellent catalyst for the alkyne addition to aldehydes. In the presence of (S)-2 (20 mol %) and Me2Zn (2 equiv) in THF at room temperature, the addition of ph
- Li, Zi-Bo,Liu, Tian-Dong,Pu, Lin
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p. 4340 - 4343
(2008/02/05)
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- Gold-catalyzed tandem cycloisomerization of alkynyloxiranes with nucleophiles: An efficient approach to 2,5-disubstituted furans
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An efficient approach to 2,5-disubstituted furans has been developed by utilizing gold-catalyzed sequential nucleophilic attack onto metal-complexed alkynes with complete regioselectivity. The reaction proceeds efficiently under mild conditions with comme
- Shu, Xing-Zhong,Liu, Xue-Yuan,Xiao, Hui-Quan,Ji, Ke-Gong,Guo, Li-Na,Qi, Chen-Ze,Liang, Yong-Min
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p. 2493 - 2498
(2008/09/19)
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- Process development and scale-up of the PPAR agonist NNC 61-4655
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A scalable synthetic route of the nonselective but PPARα-preferring potent PPAR agonist NNC 61-4655 aimed for treatment of type 2 diabetes was developed. The synthetic pathway comprises the convergent synthesis and coupling of the two key intermediates E-5-(chloropent-3-en-1-ynyl)benzene 8 (prepared in a five-step synthesis in 18% overall yield) and (S)-2-ethoxy-3-(4- hydroxyphenyl)propanoic acid isopropyl ester 9. The 2-aminoethanol salt of NNC 61-4655 was selected in a preclinical salt selection program as the appropriate salt form for further development. More than 900 g of NNC 61-4655, 2-aminoethanol was finally synthesized under GMP in 98.7% purity. In comparison to the original medicinal chemistry route, starting from phenylpropargyl aldehyde 1, the overall yield towards NNC 61-4655 could be enhanced from 24 to 37%. An improved scalable two-step synthesis for 8 was developed on a laboratory scale (≥33-35% overall yield) shortly after the GMP batch.
- Deussen, Heinz-Josef,Jeppesen, Lone,Schaerer, Norbert,Junager, Finn,Bentzen, Bjorn,Weber, Beat,Weil, Volker,Mozer, Sandor Josef,Sauerberg, Per
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p. 363 - 371
(2013/09/05)
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- TiCl4-mediated nucleophilic substitution of propargylic esters
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Direct displacement reactions of propargylic esters are reported. 10 mol% of TiCl4 were used to carry out a nucleophilic substitution. Scope and limitation of this novel reaction are described. (C) 2000 Elsevier Science Ltd.
- Mahrwald,Quint
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p. 7463 - 7468
(2007/10/03)
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- AUTOOXIDATION OF ACETYLENES AND THEIR DERIVATIVES. XXV. 1-PHENYL-4-PENTEN-1-YN-3-0L AND 1-PHENYL-4-HEXEN-1-YN-3-OL
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During the autooxidation of secondary enynyl alcohols attack by oxygen takes place at the C-H bonds at the α position to the triple and double bonds and the hydroxyl group.The initially formed unstable hydroxyhydroperoxides dissociate under the oxidation conditions into the corresponding enynyl ketones, acetylenic keto epoxydes, and products from degradation of the carbon skeleton.
- Stepin, S. G.,Tishchenko, I. G.
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p. 1771 - 1774
(2007/10/02)
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