80220-94-6Relevant academic research and scientific papers
Z-Selective phosphine promoted 1,4-reduction of ynoates and propynoic amides in the presence of water
Drikermann, Denis,Kupfer, Stephan,Seifert, Fabian,Steinmetzer, Johannes,Vilotijevic, Ivan,Zi, You
supporting information, p. 6092 - 6097 (2021/07/21)
Phosphine-mediated reductions of substituted propynoic esters and amides in the presence of water yield the partially reduced α,β-unsaturated esters and amides with highZ-selectivity. The competitivein situ ZtoE-isomerization of the product in some cases lowers theZtoEratios of the isolated α,β-unsaturated carbonyl products. Reaction time and the amounts of phosphine and water in the reaction mixture are the key experimental factors which control the selectivity by preventing or reducing the rates ofZ- toE-product isomerization. Close reaction monitoring enables isolation of theZ-alkenes with high selectivities. The computational results suggest that the reactions could be highlyZ-selective owing to the stereoselective formation of theE-P-hydroxyphosphorane intermediate.
Selective synthesis of trisubstituted pyrroles through the reactions of alkynyl Fischer carbene complexes with oxazolones
López, Julio,Velazco-Cabral, Iván,Rodríguez-DeLeón, Eloy,Villegas Gómez, Clarisa,Delgado, Francisco,Tamariz, Joaquín,Arrieta, Ana,Cossío, Fernando P.,Vázquez, Miguel A.
supporting information, p. 538 - 550 (2020/01/30)
An efficient and simple synthesis of novel trisubstituted 1H-pyrroles 4a-qvia 1,3-dipolar cycloaddition of Δ3-trifluoromethyloxazolones 2a-d with both chromium and tungsten alkynyl Fischer carbene complexes (1a-h) is described. An unexpected and unreported -CF3 group elimination process was observed in the pyrrole structure. Our experimental and theoretical data suggested that the metal fragment may be responsible for this phenomenon. The dipolar cycloaddition proceeded efficiently to produce a single regioisomer, which was unambiguously established through NMR and single-crystal X-ray diffraction studies. Nevertheless, the reaction of alkynyl carbenes bearing an α,β,γ,δ-unsaturated moiety with excess oxazolone 2a produced a polycyclic compound 6 speculatively formed through a cascade reaction involving 1,6-, 1,4- and 1,2-nucleophilic addition steps.
Consecutive Three-Component Coupling-Addition Synthesis of β-Amino Enoates and 3-Hydroxypyrazoles via Ethyl 3-Arylpropiolates
Niedballa, Jonas,Reiss, Guido J.,Müller, Thomas J. J.
supporting information, p. 5019 - 5024 (2020/07/24)
Two consecutive three-component syntheses furnishing β-amino enoates or 3-hydroxypyrazoles based upon the Sonogashira alkynylation of aryl iodides and ethyl propiolate were established in mostly excellent yields. The ethyl 3-arylpropiolate intermediates are Michael systems which are suited for concatenation with conjugate addition or cyclocondensation giving access to libraries of 21 different β-amino enoates and 17 different 3-hydroxypyrazoles. The rotational barrier of β-pyrrolidino enoates was assessed by studying the coalescence of pyrrolidinyl protons in VT-NMR spectra of electronically different substituted derivatives showing that the electronic substituent effect on the aryl group does not affect the height of the rotational barrier. This indicates that the substituents are essentially oriented orthogonally to the plane of the β-pyrrolidino enoates.
Rhodium-catalyzed enantioselective decarboxylative alkynylation of allenes with arylpropiolic acids
Grugel, Christian P.,Breit, Bernhard
, p. 1066 - 1069 (2018/02/23)
A rhodium-catalyzed chemo-, regio-, and enantioselective intermolecular decarboxylative alkynylation of terminal allenes with arylpropiolic acids is reported. Employing a Rh(I)/(R)-Tol-BINAP catalytic system, branched allylic 1,4-enynes were obtained under mild conditions. The overall utility of this protocol is exemplified by a broad functional group compatibility.
Rh-Catalyzed Asymmetric Hydrogenation of β-Substituted-β-thio-α,β-unsaturated Esters: Expeditious Access to Chiral Organic Sulfides
Liu, Gang,Han, Zhengyu,Dong, Xiu-Qin,Zhang, Xumu
, p. 5636 - 5639 (2018/09/12)
Rh/bifunctional bisphosphine-thiourea ligand (ZhaoPhos)-catalyzed asymmetric hydorgenation of both (Z)- and (E)-isomers of β-substituted-β-thio-α,β-unsaturated esters was successfully developed. This new asymmetric catalytic methodology provided highly efficient access to two enantiomers of chiral organic sulfides ethyl β-substituted-β-thio-propanoates with excellent results (up to 99% yield and >99% ee for (Z)-substrates, up to 99% yield and 98% ee for (E)-substrates, TON up to 5000), which are important intermediates in organic synthesis.
Trans -Hydroboration vs. 1,2-reduction: Divergent reactivity of ynones and ynoates in Lewis-base-catalyzed reactions with pinacolborane
Zi, You,Sch?mberg, Fritz,Seifert, Fabian,G?rls, Helmar,Vilotijevic, Ivan
supporting information, p. 6341 - 6349 (2018/09/10)
Ynones and ynoates react with pinacolborane in a divergent manner in the presence of nucleophilic phosphine catalysts. Ynones are transformed to the corresponding propargyl alcohols in good yields with high regio- and chemoselectivity. Ynoates undergo highly regio- and stereoselective trans-hydroboration to produce E-vinylboronates. Impressive divergence in reactivity of ynones and ynoates can be traced back to the mechanistic aspects of 1,2-reduction and trans-hydroboration. A comparative analysis of the two pathways paints a complex picture in which different reaction rates control selectivity in these seemingly unrelated processes and explains how sufficiently acidic protons in the reaction mixtures can be used to steer the selectivity in different directions.
3-Phenothiazinyl propiolates – Fluorescent electrophores by Sonogashira coupling of ethyl propiolate
G?tzinger, Alissa C.,Michaelis, Carina S.,Müller, Thomas J.J.
, p. 308 - 316 (2017/05/04)
Fluorescent ethyl 3-phenothiazinyl propiolates with reversible Nernstian oxidation potentials were efficiently synthesized by an improved Sonogashira coupling of aryl iodides and ethyl propiolate. The versatility of this modified alkynylation was illustrated by 13 ethyl 3-arylpropiolates in mostly excellent yields with a broad substrate scope. In addition to reversible one-electron oxidations, the title compounds reveal large Stokes shifts, high fluorescence quantum yields, and solvatochromic emission. The photophysical characteristics were corroborated and rationalized by DFT and TD-DFT calculations.
Gold(I)/Chiral N,N′-Dioxide–Nickel(II) Relay Catalysis for Asymmetric Tandem Intermolecular Hydroalkoxylation/Claisen Rearrangement
Li, Jun,Lin, Lili,Hu, Bowen,Zhou, Pengfei,Huang, Tianyu,Liu, Xiaohua,Feng, Xiaoming
supporting information, p. 885 - 888 (2017/01/13)
A highly efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π-acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′-dioxide–nickel(II) complex. A range of acyclic α-allyl β-keto esters were synthesized in high yields (up to 99 %) with good diastereoselectivities (up to 97:3) and excellent enantioselectivities (up to 99 % ee) under mild reaction conditions. These products can be easily transformed into optically active β-hydroxy esters, β-hydroxy acids, or 1,3-diols.
Visible-Light-Promoted Vinylation of Tetrahydrofuran with Alkynes through Direct C-H Bond Functionalization
Li, Jing,Zhang, Jing,Tan, Haibo,Wang, David Zhigang
supporting information, p. 2522 - 2525 (2015/05/27)
(Chemical Equation Presented) Mild and direct C-H bond functionalizations and vinylations of tetrahydrofuran with alkynes have been accomplished through visible light photocatalysis, yielding a range of vinyl tetrahydrofurans under the synergistic actions of organic dye-type photocatalyst eosin Y, tert-butyl hydroperoxide (t-BuOOH), and a 45 W household lightbulb. A significant kinetic isotope effect (KIE) was recorded, which helps shed light on the mechanistic course.
Structural design and synthesis of arylalkynyl amide-type peroxisome proliferator-activated receptor γ3 (PPAR γ3)-selective antagonists based on the helix12-folding inhibition hypothesis
Ohashi, Masao,Gamo, Kanae,Tanaka, Yuta,Waki, Minoru,Beniyama, Yoko,Matsuno, Kenji,Wada, Jun,Tenta, Masafumi,Eguchi, Jun,Makishima, Makoto,Matsuura, Nobuyasu,Oyama, Takuji,Miyachi, Hiroyuki
, p. 53 - 67 (2015/01/08)
Peroxisome proliferator-activated receptor γ3 (PPARγ3) antagonists are candidates for treatment of type 2 diabetes, obesity and osteoporosis. However, few rational design strategies are currently available. Here, we utilized the helix12 (H12)-folding inhi
