15115-58-9Relevant academic research and scientific papers
Highly Diastereoselective Synthesis of Medium-Sized Carbocycle-Fused Piperidines via Sequential Hydride Shift Triggered Double C(sp3)-H Bond Functionalization
Kataoka, Miyabi,Otawa, Yuna,Ido, Natsuki,Mori, Keiji
supporting information, p. 9334 - 9338 (2019/11/19)
Herein we report a diastereoselective synthesis of medium-sized carbocycle-fused piperidines via [1,n (n = 6, 7)]-[1,5]-sequential hydride shift triggered double C(sp3)-H bond functionalization. When cinnamylidene malonates having N,N-dibenzyl propylamine moiety were treated with 5 mol % of Yb(OTf)3, a [1,6]-[1,5]-sequential hydride shift/cyclization process proceeded to afford seven-membered carbocycle-fused piperidines with excellent diastereoselectivities. This sequential system was applicable to the synthesis of eight-membered carbocycle-fused piperidines by an unprecedented [1,7]-[1,5]-sequential hydride shift/cyclization process.
Construction of seven-and eight-membered carbocycles by Lewis acid catalyzed C(sp3)-H bond functionalization
Otawa, Yuna,Mori, Keiji
supporting information, p. 13856 - 13859 (2019/11/21)
We achieved a concise construction of seven-and eight-membered carbocycles via Lewis acid catalyzed C(sp3)-H bond functionalization. In these reactions, a quite rare [1,6 (or 7)]-hydride shift/cyclization process proceeded smoothly to afford seven-and eight-membered carbocycles with good chemical yields starting from substrates with high conformational freedom.
Synthesis of N-Substituted Condensed Tetrahydropyridine-Based Enaminones via Palladium-Catalyzed Intramolecular C–N Cross-coupling
Dou?ová, Hana,R??i?ková, Zdeňka,?im?nek, Petr
supporting information, p. 670 - 684 (2018/01/22)
A number of β-enaminones with secondary amino group (alkyl, cyclopropyl, and aryl) were prepared from corresponding β-diketones. Two general protocols for their palladium-catalyzed intramolecular C–N cross-coupling were established to give corresponding N-substituted condensed tetrahydropyridines in good yields. The methodology is applicable for a wide variety of structural motifs. The work also extends the applicability of novel, recently established, palladium precatalysts to new substrates.
Regioselectivity inversion tuned by iron(iii) salts in palladium-catalyzed carbonylations
Huang, Zijun,Cheng, Yazhe,Chen, Xipeng,Wang, Hui-Fang,Du, Chen-Xia,Li, Yuehui
supporting information, p. 3967 - 3970 (2018/04/23)
Impactful regioselectivity control is crucial for cost-effective chemical synthesis. By using cheap and abundant iron(iii) salts, the hydroxycarbonylations of both aromatic and aliphatic alkenes were significantly enhanced in both reactivity and selectivity (iso/n or n/iso up to >99:1). Moreover, Pd-catalyzed carbonylation selectivity can be switched from branched to linear by using different Fe(iii) salts. In addition, similar results were obtained for the carbonylation of secondary alcohols.
An intramolecular C-N cross-coupling of β-enaminones: A simple and efficient way to precursors of some alkaloids of Galipea officinalis
Douov, Hana,Hork, Radim,Ruikov, Zdeka,imunek, Petr
supporting information, p. 884 - 892 (2015/08/24)
2-Aroylmethylidene-1,2,3,4-tetrahydroquinolines with the appropriate substituents can be suitable precursors for the synthesis of alkaloids from Galipea officinalis (cuspareine, galipeine, galipinine, angustureine). However, only two, rather low-yielding procedures for their synthesis are described in the literature. We have developed a simple and efficient protocol for an intramolecular, palladium or copper-catalysed amination of both chloro- and bromo-substituted 3-amino-1,5-diphenylpent-2-en-1-ones leading to the above-mentioned tetrahydroquinoline moiety. The methodology is superior to the methods published to date.
Effect of chain length on radical to carbanion cyclo-coupling of bromoaryl alkyl-linked oxazolines: 1,3-Areneotropic migration of oxazolines
Marshall, Laura J.,Roydhouse, Mark D.,Slawin, Alexandra M. Z.,Walton, John C.
, p. 898 - 911 (2007/10/03)
(Chemical Equation Presented) 2-Halophenylalkyl-2-oxazolines with alkyl chain spacers of two to six C atoms (n = 0-4) were prepared and their S RN1-type reactions with several base systems examined. The best conditions to promote cyclocoupling to the corresponding benzocycloalkane derivatives involved use of LDA in THF. The precursors with 3-C-atom and 4-C-atom spacers gave good yields of 2-(1′-phenylindan-1′-yl)-2- oxazolines and 2-(1-phenyl-1,2,3,4-tetrahydronaphthalen-1-yl)-2-oxazoline, respectively. The major products from the precursor with a 5-C-atom spacer were derivatives of benzocycloheptane in which the oxazoline group had undergone a novel areneotropic migration from the end of the spacer to the benzo ring. The product from reaction of the corresponding 2-C-atom precursor was a 9-oxazolinophenanthrene derivative. EPR spectroscopy showed the intermediates of the LDA-promoted reactions to be radical anions of the product benzocycloalkanes. This supported an SRN1-type chain mechanism involving initial production of aryl radicals connected to azaenolate ions via the spacer groups. Intramolecular radical to carbanion coupling then generated ring-closed benzocycloalkane radical anions that transferred an electron to more precursor. Diastereoselective radical to carbanion cyclo-coupling reactions were carried out with 2-bromophenylpropyl precursors containing chiral 2-oxazolines. The diastereoselectivity achievable was modest, but the product diastereoisomeric Indane derivatives were easily separable by chromatography.
Heteroatom bridged metallocene compounds for olefin polymerization
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, (2008/06/13)
This invention relates to a transition metal compound represented by the formula: wherein M is a group 3, 4, 5 or 6 transition metal atom, or a lanthanide metal atom, or actinide metal atom; E is: 1) a substituted or unsubstituted indenyl ligand that is bonded to Y through the four, five, six or seven position of the indenyl ring, or 2) a substituted or unsubstituted heteroindenyl ligand that is bonded to Y through the four, five or six position of the heteroindenyl ring, provided that the bonding position is not the same as the position of the ring heteroatom, or 3) a substituted or unsubstituted fluorenyl ligand that is bonded to Y through the one, two, three, four, five, six, seven or eight position of the fluorenyl ring, or 4) a substituted or unsubstituted heterofluorenyl ligand that is bonded to Y through the one, two, three, four, five or six position of the heteroindenyl ring, provided that the bonding position is not the same as the position of the ring heteroatom; A is a substituted or unsubstituted cyclopentadienyl ligand, a substituted or unsubstituted heterocyclopentadienyl ligand, a substituted or unsubstituted indenyl ligand, a substituted or unsubstituted heteroindenyl ligand, a substituted or unsubstituted fluorenyl ligand, a substituted or unsubstituted heterofluorenyl ligand, or other mono-anionic ligand; Y is a Group 15 or 16 bridging heteroatom substituent that is bonded via the heteroatom to E and A; and X are, independently, univalent anionic ligands, or both X are joined and bound to the metal atom to form a metallocycle ring, or both X join to form a chelating ligand, a diene ligand, or an alkylidene ligand. This invention further relates to catalyst systems comprising the above transiotioon metal compounds, activators and optional supports and their use to polymerize or oligomerize olefins.
Radical-carbanion cyclo-coupling in armed aromatics: Overriding steric hindrance to ring closure
Roydhouse, Mark D.,Walton, John C.
, p. 4453 - 4455 (2007/10/03)
ω-(2-Halophenyl)alkyl-2-oxazolines were prepared and reacted via base promoted intramolecular coupling of radical with carbanionic centres to yield 1-phenyl-1-oxazolino-indan and -tetralin derivatives containing quaternary C-atoms. The Royal Society of Chemistry 2005.
A Convergent Method for the Synthesis of Highly Enantiomerically Enriched Cyclic Silanes with Silicon-Centered Chirality
Oestreich, Martin,Schmid, Ulrike K.,Auer, Gertrud,Keller, Manfred
, p. 2725 - 2739 (2007/10/03)
A preparatively straightforward methodology has been developed which allows the assembly of silicon-containing carbocycles as mixtures of diastereomers with silicon as the sole center of stereogenic information. One-step construction of the chiral cyclic silanes is realized by reaction of equimolar amounts of a dibromide and a chirally modified dichlorosilane under Barbier conditions giving access to several monofunctionalized 1-sila-1,2,3,4-tetrahydronaphthalenes and a corresponding phenanthrene derivative. Facile large scale syntheses of 3-(2-bromoaryl)propyl bromides as well as dichlorosilanes have been elaborated. This highly convergent methodology relies on the novel (-)-menthyloxy-substituted dichlorosilanes, which have the chiral auxiliary for the subsequent optical resolution installed. These enantiopure dichlorosilanes are useful building blocks for a general and modular one-step approach to silanes with silicon-centered chirality since this strategy avoids the linear sequences reported in literature. The optical resolution has been exemplarily optimized for the 1-phenyl-1-sila-1,2,3,4- tetrahydronaphthalene derivative and the absolute configuration has been established by X-ray crystallography. The chiral auxiliary is stereospecifically displaced by simple reduction providing the highly enantioenriched silane (er = 98:2) which is enantiospecifically chlorinated as verified by a Walden inversion at silicon.
Amine- and ether-chelated aryllithium reagents - Structure and dynamics
Reich, Hans J.,Goldenberg, Wayne S.,Sanders, Aaron W.,Jantzi, Kevin L.,Tzschucke, C. Christoph
, p. 3509 - 3521 (2007/10/03)
Chelation and aggregation in phenyllithium reagents with potential 6- and 7-ring chelating amine (2, 3) and 5-, 6-, and 7-ring chelating ether (4, 5, 6) ortho substituents have been examined utilizing variable temperature 6Li and 13C NMR spectroscopy, 6Li and 15N isotope labeling, and the effects of solvent additives. The 5- and 6-ring ether chelates (4, 5) compete well with THF, but the 6-ring amine chelate (2) barely does, and 7-ring amine chelate (3) does not. Compared to model compounds (e.g., 2-ethylphenyllithium 7), which are largely monomeric in THF, the chelated compounds all show enhanced dimerization (as measured by K = [D]/[M]2) by factors ranging from 40 (for 6) to more than 200 000 (for 4 and 5). Chelation isomers are seen for the dimers of 5 and 6, but a chelate structure could be assigned only for 2-(2-dimethylaminoethyl)phenyllithium (2), which has an A-type structure (both amino groups chelated to the same lithium in the dimer) based on NMR coupling in the 15N, 6Li labeled compound. Unlike the dimer, the monomer of 2 is not detectably chelated. With the exception of 2-(methoxymethyl)phenyllithium (4), which forms an open dimer (12) and a pentacoordinate monomer (13), the lithium reagents all form monomeric nonchelated adducts with PMDTA.
