54781-35-0Relevant academic research and scientific papers
Asymmetric Catalysis with Ethylene. Synthesis of Functionalized Chiral Enolates
Biswas, Souvagya,Page, Jordan P.,Dewese, Kendra R.,RajanBabu
supporting information, p. 14268 - 14271 (2015/12/01)
Trialkylsilyl enol ethers are versatile intermediates often used as enolate surrogates for the synthesis of carbonyl compounds. Yet there are no reports of broadly applicable, catalytic methods for the synthesis of chiral silyl enol ethers carrying latent functionalities useful for synthetic operations beyond the many possible reactions of the silyl enol ether moiety itself. Here we report a general procedure for highly catalytic (substrate:catalyst ratio up to 1000:1) and enantioselective (92% to 98% major enantiomer) synthesis of such compounds bearing a vinyl group at a chiral carbon at the β-position. The reactions, run under ambient conditions, use trialkylsiloxy-1,3-dienes and ethylene (1 atm) as precursors and readily available (bis-phosphine)-cobalt(II) complexes as catalysts. The silyl enolates can be readily converted into novel enantiopure vinyl triflates, a class of highly versatile cross-coupling reagents, enabling the syntheses of other enantiomerically pure, stereodefined trisubstituted alkene intermediates not easily accessible by current methods. Examples of Kumada, Stille, and Suzuki coupling reactions are illustrated.
Iridium-catalyzed enantioselective allylation of silyl enol ethers derived from ketones and α,β-unsaturated ketones
Liang, Xiao,Wei, Kun,Yang, Yu-Rong
supporting information, p. 17471 - 17474 (2015/12/09)
The unified Ir-catalyzed enantioselective allylic substitution reactions of silyl enol ethers derived from ketones and α,β-unsaturated ketones with branched, racemic allylic alcohols are described. This transformation is catalyzed by the Carreira system and proceeds without fluoride, and with high ee and b:l ratio. The synthetic utility of this method was illustrated by the concise enantioselective total synthesis of marine natural products calyxolane A, B and by the assignment of the absolute configuration of calyxolane A.
A highly enantioselective hydrogenation of silyl enol ethers catalyzed by chiral frustrated lewis pairs
Wei, Simin,Du, Haifeng
supporting information, p. 12261 - 12264 (2014/10/16)
Using a simple combination of tri-tert-butylphosphine and chiral borane generated in situ by the hydroboration of chiral diene with HB(C 6F5)2 as a frustrated Lewis pair catalyst, a highly enantioselective metal-free hydrogenation of silyl enol ethers was successfully realized to furnish a variety of optically active secondary alcohols in 93-99% yields with 88->99% ees.
Synthetic studies on and mechanistic insight into [W(CO) 5(L)]-catalyzed stereoselective construction of functionalized bicyclo[5.3.0]decane frameworks
Onizawa, Yuji,Hara, Masahiro,Hashimoto, Takuya,Kusama, Hiroyuki,Iwasawa, Nobuharu
supporting information; experimental part, p. 10785 - 10796 (2010/11/19)
Stereoselective preparation of a variety of synthetically useful functionalized bicyclo[5.3.0]decane derivatives was achieved by tandem cyclization of 3-siloxy-1,3,9-triene-7-yne derivatives based on the electrophilic activation of alkynes catalyzed by [W(CO)5(L)], The reaction proceeded smoothly under photoirradiation, and various substrates were cyclized to give the corresponding bicyclic compounds with up to four chiral centers stereospecifically. Reactions of siloxydienes with a silyl substituent as an equivalent of a hydroxyl group also proceeded with wide generality to afford silyl-substituted bicyclo[5.3.0]decanes, which were highly useful as synthetic intermediates. Stereochemical studies concerning the silyl enol ether moiety suggested that two types of reaction path way for the formation of seven-membered rings were present. The reaction of (Z)-enol silyl ethers proceeded through Cope rearrangement of cis-divinylcyclopropane intermediates, and that of (E)-enol silyl ethers by 1,4-addition of the dienyl tungsten species at the position δ to the metal atom. In the reactions of siloxydiene derivatives with silyl substituents, all possible diastereomers could be synthesized stereoselectively by changing the geometry of the silyl enol ether and enyne moieties.
Efficient control of π-alkyne and vinylidene complex pathways for the W(CO)5(L)-catalyzed synthesis of two types of nitrogen-containing bicyclic compounds
Onizawa, Yuji,Kusama, Hiroyuki,Iwasawa, Nobuharu
, p. 802 - 803 (2008/09/20)
When ω-acetylenic dienol silyl ethers containing NMs part in the tether were treated with a catalytic amount of W(CO)6 under photoirradiation, 2-azabicyclo[3.3.0]octanes were obtained in good yield via π-alkyne complexes. On the other hand, treatment of the same substrates with a catalytic amount of W(CO)6 in the presence of n-Bu3N under the same reaction conditions gave 3-azabicyclo[3.3.0]octanes in good yield exclusively via vinylidene complexes. Thus, the π-alkyne and vinylidene complex pathways are easily controlled by using a catalytic amount of W(CO)5(L) and an amine. Copyright
W(CO)5(L)-catalyzed tandem intramolecular cyclopropanation/cope rearrangement for the stereoselective construction of bicyclo[5.3.0]decane framework
Kusama, Hiroyuki,Onizawa, Yuji,Iwasawa, Nobuharu
, p. 16500 - 16501 (2007/10/03)
Utilizing the biscarbene character of electrophilically activated alkynes, a novel tandem intramolecular cyclopropanation/Cope rearrangement of 3-siloxy-1,3,9-trien-7-ynes catalyzed by W(CO)5(L) for the stereoselective construction of bicyclo[5.3.0]decane framework is achieved. When 3-siloxy-1,3,9-trien-7-ynes were treated with a catalytic amount of W(CO)6 under photoirradiation, bicyclo[5.3.0]decanes were obtained in good yield stereoselectively. In this reaction, the Cope rearrangement of the divinylcyclopropane intermediates, generated by the intramolecular cyclopropanation of 3-siloxy-1,3,9-trien-7-ynes based on the W(CO)5(L)-catalyzed electrophilic activation of alkynes, occurs to give synthetically useful functionalized bicyclo[5.3.0]decane derivatives stereoselectively. Copyright
A general one-pot synthesis of vinyl-thiiranes and conjugated dienes
Maciagiewicz,Dybowski,Skowronska
, p. 3791 - 3794 (2007/10/03)
The first general synthesis of vinyl-thiiranes 5 and an efficient preparation of conjugated dienes 6 and 7 based on thio, and selenophosphates is described.
Thiophosphates and selenophosphates in organic synthesis. A new approach to exocyclic olefins and bicyclic enones
Skowrońska, Aleksandra,Krawczyk, Ewa,Koprowski, Marek,Dybowski, Piotr
, p. 409 - 412 (2007/10/03)
Efficient synthesis of α-methylene-cycloalkanones, α-methylene-lactones and α-alkylidene-lactones as well as bicyclic enones were developed using thiophosphates 3, 9, 15 and selenophosphates 4 as key intermediates.
Annulation by Sequential Doubla Michael Reaction; Synthesis of Decalones and Its Application to the Syntheses of ε-Cadinene, Khusitone and Khusilal
Hagiwara, Hisahiro,Akama, Tsutomu,Okano, Akihiro,Uda, Hisashi
, p. 2173 - 2184 (2007/10/02)
Reaction of kinetic enolates or the trimethylsilyl enol ethers of 1-acetylcyclohexenes with α,β-unsaturated carbonyl compounds affords 4-substituted 1-decalone derivatives under basic or Lewis acidic conditions.The reaction with acrylates of chiral alcohols has achieved 70percent diastereoselection.Application of these reactions has enabled syntheses of ε-cadinene, khusitone and khusial to be accomplished.
Enolate Ions, II. - Convenient Synthesis of 3,4-Dihydro-2,4-dioxo-2H-pyrans and 2-Pyrones. - Enolate Ions as Synthetic Equivalents of 1,3-Dianions. - Crystal and Molecular Structure of Ethyl 6-Ethoxy-3,4-dihydro-3,3-dimethyl-2,4-dioxo-2H-pyran-5-carboxyla
Saalfrank, Rolf W.,Guendel, Juergen,Rossmann, Guenther,Hanek, Martin,Rost, Walter,et al.
, p. 1175 - 1183 (2007/10/02)
Reaction of dimethylmalonyl chloride (6a) or cyclic 1,1-dicarbonyl dichlorides 6b-d with two equivalents of lithium enolates 7, 22, and silyl enol ethers 8, respectively, yields 3,4-dihydro-2,4-dioxo-2H-pyrans 10, 24, or spiro compounds 11-13, 25-27.The s
