94118-13-5Relevant academic research and scientific papers
Site- and regioselective silaborative C-C cleavage of 1-alkyl-2-methylenecyclopropanes using a platinum catalyst with a sterically demanding silylboronic ester
Ohmura, Toshimichi,Taniguchi, Hiroki,Suginome, Michinori
, p. 3074 - 3077 (2015)
1-Alkyl-2-methylenecyclopropanes react with silylboronic esters under mild conditions in the presence of a phosphine-free platinum catalyst, giving 3-substituted 2-boryl-4-silyl-1-butenes through selective cleavage of the less hindered proximal C-C bond o
Crossed Regio- and Enantioselective Iron-Catalyzed [4+2]-Cycloadditions of Unactivated Dienes
Braconi, Elena,Cramer, Nicolai
, (2021/12/22)
The cyclohexene motif is ubiquitous in nature and specialty chemicals. A straightforward selective access to chiral cyclohexenes from unactivated dienes and dienophiles is not feasible by classical Diels–Alder reaction and constitutes an unsolved syntheti
Regio- and Diastereoselective Iron-Catalyzed [4+4]-Cycloaddition of 1,3-Dienes
Kennedy, C. Rose,Zhong, Hongyu,MacAulay, Rachel L.,Chirik, Paul J.
supporting information, p. 8557 - 8573 (2019/06/04)
A family of single-component iron precatalysts for the [4+4]-cyclodimerization and intermolecular cross-[4+4]-cycloaddition of monosubstituted 1,3-dienes is described. Cyclooctadiene products were obtained with high regioselectivity, and catalyst-controlled access to either cis- or trans-diastereomers was achieved using 4-substituted diene substrates. Reactions conducted either with single-component precatalysts or with iron dihalide complexes activated in situ proved compatible with common organic functional groups and were applied on multigram scale (up to >100 g). Catalytically relevant, S = 1 iron complexes bearing 2-(imino)pyridine ligands, (RPI)FeL2 (RPI = [2-(2,6-R2-C6H3-Na-CMe)-C5H4N] where R = iPr or Me, L2 = bis-olefin), were characterized by single-crystal X-ray diffraction, M??bauer spectroscopy, magnetic measurements, and DFT calculations. The structural and spectroscopic parameters are consistent with an electronic structure description comprised of a high spin iron(I) center (SFe = 3/2) engaged in antiferromagnetically coupling with a ligand radical anion (SPI = -1/2). Mechanistic studies conducted with these single-component precatalysts, including kinetic analyses, 12C/13C isotope effect measurements, and in situ M??bauer spectroscopy, support a mechanism involving oxidative cyclization of two dienes that determines regio- and diastereoselectivity. Topographic steric maps derived from crystallographic data provided insights into the basis for the catalyst control through stereoselective oxidative cyclization and subsequent, stereospecific allyl-isomerization and C-C bond-forming reductive elimination.
A General Nickel-Catalyzed Kumada Vinylation for the Preparation of 2-Substituted 1,3-Dienes
Fiorito, Daniele,Folliet, Sarah,Liu, Yangbin,Mazet, Clément
, p. 1392 - 1398 (2018/02/14)
The identification of two nickel(II) precatalysts for the preparation of 2-substituted 1,3-dienes by a Kumada cross-coupling between vinyl magnesium bromide and vinyl phosphates is described. This is noteworthy as engaging only one vinyl derivative in a transition-metal-catalyzed cross-coupling reaction is already reputedly challenging. Salient features of this method are its operational simplicity, the mild reaction conditions, the low catalyst loadings, the short reaction times, its scalability, and the use of stoichiometric quantities of each coupling partner. The tolerance of the two nickel catalysts to an important number of reactive functional groups and their compatibility with structurally complex molecular architectures has been extensively delineated. A Negishi variant of the reaction has been developed for even more sensitive organic functions such as ester or nitrile. Several other conjugated 1,3-dienes with various substitution patterns have been prepared by combining commercial alkenyl Grignard reagents and/or readily available alkenyl enol phosphates. Proper choice of the nickel catalyst and the reaction temperature gave access to a variety of different olefin isomers with high levels of stereocontrol. Overall, this approach affords conjugated dienes that would not be accessible otherwise and therefore provides a valuable complement to existing methods.
Structural and functional insights into asymmetric enzymatic dehydration of alkenols
Nestl, Bettina M.,Geinitz, Christopher,Popa, Stephanie,Rizek, Sari,Haselbeck, Robert J.,Stephen, Rosary,Noble, Michael A.,Fischer, Max-Philipp,Ralph, Erik C.,Hau, Hoi Ting,Man, Henry,Omar, Muhiadin,Turkenburg, Johan P,Van Dien, Stephen,Culler, Stephanie J.,Grogan, Gideon,Hauer, Bernhard
, p. 275 - 281 (2017/02/23)
The asymmetric dehydration of alcohols is an important process for the direct synthesis of alkenes. We report the structure and substrate specificity of the bifunctional linalool dehydratase isomerase (LinD) from the bacterium Castellaniella defragrans that catalyzes in nature the hydration of β-myrcene to linalool and the subsequent isomerization to geraniol. Enzymatic kinetic resolutions of truncated and elongated aromatic and aliphatic tertiary alcohols (C5-C15) that contain a specific signature motif demonstrate the broad substrate specificity of LinD. The three-dimensional structure of LinD from Castellaniella defragrans revealed a pentamer with active sites at the protomer interfaces. Furthermore, the structure of LinD in complex with the product geraniol provides initial mechanistic insights into this bifunctional enzyme. Site-directed mutagenesis confirmed active site amino acid residues essential for its dehydration and isomerization activity. These structural and mechanistic insights facilitate the development of hydrating catalysts, enriching the toolbox for novel bond-forming biocatalysis.
Enantioselective (Formal) Aza-diels-alder reactions with non-danishefsky-type dienes
Tambar, Uttam K.,Lee, Sharon K.,Leighton, James L.
supporting information; experimental part, p. 10248 - 10250 (2010/09/05)
Enantioselective (formal) aza-Diels-Alder reactions between acylhydrazones and non-Danishefsky-type dienes have been developed. The reactions are promoted by a simple and economical chiral silicon Lewis acid and are typically conducted at ambient temperature. Both glyoxylate- and aliphatic aldehyde-derived hydrazones may be employed, as may variously substituted dienes, leading to the synthesis of a diverse array of tetrahydropyridines with good to excellent levels of enantioselectivity.
An improved 1,3-diene synthesis from alkyne and ethylene using cross-enyne metathesis
Tonogaki, Keisuke,Mori, Miwako
, p. 2235 - 2238 (2007/10/03)
Synthesis of 1,3-diene from alkyne and ethylene (1 atm) was improved using ruthenium carbene complex 1b having heterocyclic carbene as a ligand. In this reaction, the heteroatom at the propargylic position was not required, although the reaction of alkyne
Rearrangement of allylic and propargylic alcohols catalyzed by the combined use of tetrabutylammonium perrhenate(VII) and p-toluenesulfonic acid
Narasaka,Kusama,Hayashi
, p. 2059 - 2068 (2007/10/02)
Allylic rearrangement and/or dehydration reaction of allylic alcohols proceeds smoothly by the use of catalytic amounts of tetrabutylammonium perrhenate and p-toluenesulfonic acid hydrate. Treatment of propargylic alcohols with the catalysts at room temperature affords the rearranged products, α,β-unsaturated carbonyl compounds, while β,γ-unsaturated ketones are obtained as main products by the reaction in refluxing 1,2-dichloroethane. The application of this catalytic system is also described for the preparation of some synthetic intermediates.
Silicon-Directed Diene Synthesis
Brown, Paul A.,Bonnert, Roger V.,Jenkins, Paul R.,Lawrence, Nicholas J.,Selim, Mohammed R.
, p. 1893 - 1900 (2007/10/02)
A synthesis of 2-substituted-1,3-dienes is reported which uses silicon as a control element: eight aldehydes were converted into α-silyl ketones by treatment with trimethylsilylmethylmagnesium chloride and rapid Collins oxidation.Addition of vinylmagnesiu
