83947-58-4Relevant academic research and scientific papers
ISOMERIZATION OF ALKENES
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Page/Page column 20-21; 23, (2020/04/25)
The present invention relates to an isomerization method for alkenes, comprising of reaction an alkene with a Ni(I)-compound. By this method, E-Alkenes are obtained in excellent yield.
Ru-catalyzed isomerization of ω-alkenylboronates towards stereoselective synthesis of vinylboronates with subsequent: In situ functionalization
Ho, Guo-Ming,Marek, Ilan,Segura, Lucas
, p. 5944 - 5949 (2020/07/10)
The stereoselective preparation of synthetically versatile vinylboronates from ω-alkenylboronates is achieved through a ruthenium-catalyzed isomerization reaction. A variety of di- A nd trisubstituted vinylboronates were conveniently produced and could be
Aliphatic α-Boryl-α-bromoketones: Synthesis and Reactivity
Ivon, Yevhen M.,Kuchkovska, Yuliya O.,Voitenko, Zoya V.,Grygorenko, Oleksandr O.
, p. 3367 - 3377 (2020/03/13)
A protocol for the preparation of α-boryl-α-bromoketones from alkenyl MIDA boronates was developed and applied to functionalized aliphatic derivatives. The reaction sequence included regioselective hydroxybromination of olefin moiety, followed by oxidation of alcohol group with Dess–Martin periodinane. The target trifunctional boronate-containing derivatives were obtained in up to 94 % yield over two steps starting from alkenyl MIDA boronates. In some cases, functional groups present in the substrate participated in the bromohydroxylation step via intramolecular nucleophilic attack at the bromonium cation leading to cyclic products. Additionally, the reactivity of aliphatic α-boryl-α-bromoketones was illustrated by nucleophilic substitution at the α-C atom and heterocyclization reactions.
Methylenespiro[2.3]hexanes via Nickel-Catalyzed Cyclopropanations with [1.1.1]Propellane
Yu, Songjie,Noble, Adam,Bedford, Robin B.,Aggarwal, Varinder K.
supporting information, p. 20325 - 20334 (2019/12/30)
[1.1.1]Propellane is a highly strained tricyclic hydrocarbon whose reactivity is dominated by addition reactions across the central inverted bond to provide bicyclo[1.1.1]pentane derivatives. These reactions proceed under both radical and two-electron pathways, hence, providing access to a diverse array of products. Conversely, transition metal-catalyzed reactions of [1.1.1]propellane are underdeveloped and lack synthetic utility, with reported examples generally yielding mixtures of ring-opened structural isomers, dimers, and trimers, often with poor selectivity. Herein, we report that nickel(0) catalysis enables the use of [1.1.1]propellane as a carbene precursor in cyclopropanations of a range of functionalized alkenes to give methylenespiro[2.3]hexane products. Computational studies provide support for initial formation of a Ni(0)-[1.1.1]propellane complex followed by concerted double C-C bond activation to give the key 3-methylenecyclobutylidene-nickel intermediate.
E-Olefins through intramolecular radical relocation
Kapat, Ajoy,Sperger, Theresa,Guven, Sinem,Schoenebeck, Franziska
, p. 391 - 396 (2019/02/03)
Full control over the selectivity of carbon-carbon double-bond migrations would enable access to stereochemically defined olefins that are central to the pharmaceutical, food, fragrance, materials, and petrochemical arenas. The vast majority of double-bond migrations investigated over the past 60 years capitalize on precious-metal hydrides that are frequently associated with reversible equilibria, hydrogen scrambling, incomplete E/Z stereoselection, and/or high cost. Here, we report a fundamentally different, radical-based approach.We showcase a nonprecious, reductant-free, and atom-economical nickel (Ni)(I)-catalyzed intramolecular 1,3-hydrogen atom relocation to yield E-olefins within 3 hours at room temperature. Remote installations of E-olefins over extended distances are also demonstrated.
Synthesis of vinyl boronates from aldehydes by a practical boron-Wittig reaction
Coombs, John R.,Zhang, Liang,Morken, James P.
supporting information, p. 1708 - 1711 (2015/04/14)
A highly stereoselective boron-Wittig reaction between stable and readily accessible 1,1-bis(pinacolboronates) and aldehydes furnishes a variety of synthetically useful di- and trisubstituted vinyl boronate esters.
Double-Bond Isomerization: Highly Reactive Nickel Catalyst Applied in the Synthesis of the Pheromone (9 Z,12 Z)-Tetradeca-9,12-dienyl Acetate
Weber, Felicia,Schmidt, Anastasia,R?se, Philipp,Fischer, Michel,Burghaus, Olaf,Hilt, Gerhard
supporting information, p. 2952 - 2955 (2015/06/30)
A highly reactive nickel catalyst comprising NiCl2(dppp) or NiCl2(dppe) with zinc powder, ZnI2 and Ph2PH, was applied in the isomerization of terminal alkenes to Z-2-alkenes. The double-bond geometry of the 2-alkene can be controlled via the reaction temperature to yield the 2-Z-alkenes in excellent yields and high Z-selectivities. The formation of other constitutional isomers, such as 3-alkenes, is suppressed on the basis of the proposed mechanism via a 1,2-hydride shift from the metal to the Ph2P ligand. The nickel-catalyzed isomerization reaction was then applied in the synthesis of (9Z,12Z)-tetradeca-9,12-dienyl acetate, a pheromone with a 2Z,5Z-diene subunit.
Enantioselective syn and anti homocrotylation of aldehydes: Application to the formal synthesis of spongidepsin
Lin, Hongkun,Tian, Leiming,Krauss, Isaac J.
supporting information, p. 13176 - 13182 (2015/10/28)
Whereas crotylboration has been a useful method for synthesis of stereochemically complex products, we have shown that homocrotylboration can be achieved with cyclopropanated crotylation reagents, and that the stereoselectivity of the reaction can be predicted by analogous models. This paper presents a full account of this work, including the first examples of asymmetric anti homocrotylation. The scope of this reaction is demonstrated with highly enantioselective homocrotylation of both aliphatic and aromatic aldehydes, as well as double diastereoselection studies. An application of the synthesis of the marine natural product spongidepsin is presented, as well as streamlined syntheses of homocrotylation reagents.
Z -selective homodimerization of terminal olefins with a ruthenium metathesis catalyst
Keitz, Benjamin K.,Endo, Koji,Herbert, Myles B.,Grubbs, Robert H.
supporting information; experimental part, p. 9686 - 9688 (2011/08/05)
The cross-metathesis of terminal olefins using a novel ruthenium catalyst results in excellent selectivity for the Z-olefin homodimer. The reaction was found to tolerate a large number of functional groups, solvents, and temperatures while maintaining excellent Z-selectivity, even at high reaction conversions.
PYRROLO [2, 3 - B] PYRAZINE - 7 - CARBOXAMIDE DERIVATIVES AND THEIR USE AS JAK AND SYK INHIBITORS
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Page/Page column 150-151, (2011/12/04)
The present invention relates to the use of novel pyrrolopyrazine derivatives of Formula (I), wherein the variables Q and R, R2, and R3 are defined as described herein, which inhibit JAK and SYK and are useful for the treatment of auto-immune and inflammatory diseases.
