1817-49-8Relevant academic research and scientific papers
Highly diastereoselective sequential Michael-aldol reactions of methyl 2-chloro-2-cyclopropylideneacetate with Grignard reagents and aldehydes
Dalai, Suryakanta,Limbach, Michael,Zhao, Ligang,Tamm, Markus,Sevvana, Madhumati,Sokolov, Viktor V.,De Meijere, Armin
, p. 471 - 479 (2006)
Grignard reagents, especially isopropylmagnesium chloride, smoothly undergo Michael addition onto methyl 2-bromo- and 2-chloro-2-cyclopropylideneacetate (1-Cl), and the thus formed magnesium enolates are particularly efficiently trapped with aromatic aldehydes. This one-pot reaction provides highly substituted chlorohydrines, mostly in high yields (10 out of 18 examples with 72-92%) and as pure (2S*,3R*)-diastereomers (anti-aldols). These chlorohydrines can be transformed to Darzens-type α,β-epoxyesters in good yields, as demonstrated for one example. Georg Thieme Verlag Stuttgart.
Construction of an ortho-phenol polymer
Xu, Ming-Hua,Lin, Zhi-Ming,Pu, Lin
, p. 6235 - 6238 (2001)
Synthesis and study of an ortho-phenol polymer, a highly functionalized polyphenylene, have been conducted. A dibromo ortho-biphenol monomer was synthesized and its homocoupling in the presence of Ni(1,5-cyclooctadiene)2 followed by hydrolysis led to the formation of an ortho-phenol polymer. This polymer was soluble in common organic solvents. It was characterized by gel permeation chromatography, UV-vis, IR, 1H and 13C NMR spectroscopic methods. The use of this polymer in the Lewis acid-catalyzed reaction of phenylacetylene with benzaldehyde in the presence of diethylzinc was studied. It was found that the polymer when treated with 1/4 equiv. (relative to the phenol unit of the polymer) of Ti(OiPr)4 generated a much more active Lewis acid catalyst than when treated with excess Ti(OiPr)4. This indicates that different types of catalytic sites in the polymer have been produced under these conditions.
Enantioselective addition of terminal alkynes to aldehydes catalyzed by a Cu(I)-TRAP complex
Asano, Yohsuke,Hara, Kenji,Ito, Hajime,Sawamura, Masaya
, p. 3901 - 3904 (2007)
The addition of terminal alkynes to aromatic aldehydes was carried out under mild conditions in the presence of a Cu-phosphine complex, which was prepared in situ from Cu(O-t-Bu) and TRAP chiral bisphosphine, to yield enantiomerically enriched propargyl alcohols with moderate enantioselectivities. Furthermore, according to stoichiometric reactions, the reaction presumably involves the addition of a TRAP-coordinated Cu(I) acetylide to an aldehyde.
Adding two active silver atoms on Au25 nanoparticle
Yao, Chuanhao,Chen, Jishi,Li, Man-Bo,Liu, Liren,Yang, Jinlong,Wu, Zhikun
, p. 1281 - 1287 (2015)
Alloy nanoparticles with atomic monodispersity is of importance for some fundamental research (e.g., the investigation of active sites). However, the controlled preparation of alloy nanoparticles with atomic monodispersity has long been a major challenge. Herein, for the first time a unique method, antigalvanic reduction (AGR), is introduced to synthesize atomically monodisperse Au25Ag2(SC2H4Ph)18 in high yield (89%) within 2 min. Interestingly, the two silver atoms in Au25Ag2(SC2H4Ph)18 do not replace the gold atoms in the precursor particle Au25(SC2H4Ph)18 but collocate on Au25, which was supported by experimental and calculated results. Also, the two silver atoms are active to play roles in stabilizing the alloy nanoparticle, triggering the nanoparticle fluorescence and catalyzing the hydrolysis of 1,3-diphenylprop-2-ynyl acetate.
Propargylation of CoQ0 through the Redox Chain Reaction
Pawlowski, Robert,Stodulski, MacIej,Mlynarski, Jacek
, p. 683 - 692 (2022/01/04)
An efficient catalytic propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf)3 and Hantzsch ester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given transformation is also discussed.
Tunable Gold-catalyzed Reactions of Propargyl Alcohols and Aryl Nucleophiles
Fiksdahl, Anne,Jónsson, Helgi Freyr,Lomeland, Sondre,Reiers?lmoen, Ann Christin,Solvi, Thomas Nordb?
, (2022/03/15)
Gold-catalyzed transformations of 1,3-diarylpropargyl alcohols and various aryl nucleophiles were studied. Selective tunable synthetic methods were developed for 1,1,3-triarylallenes, diaryl-indenes and tetraaryl-allyl target products by C3 nucleophilic substitution and subsequent intra- or intermolecular hydroarylation, respectively. The reactions were scoped with regards to gold(I)/(III) catalysts, solvent, temperature, and electronic and steric effects of both the diarylpropargyl alcohol and the aryl nucleophiles. High yields of triaryl-allenes and diaryl-indenes by gold(III) catalysis were observed. Depending on the choice of aryl nucleophile and control of reaction temperature, different product ratios have been obtained. Alternatively, tetraaryl-allyl target products were formed by a sequential one-pot tandem process from appropriate propargyl substrates and two different aryl nucleophiles. Corresponding halo-arylation products (I and Br; up to 95 % 2-halo-diaryl-indenes) were obtained in a one-pot manner in the presence of the respective N-halosuccinimides (NIS, NBS).
Enantioselective [3 + 2] annulation of 4-isothiocyanato pyrazolones and alkynyl ketones under organocatalysis
Wang, Wenyao,Wei, Shiqiang,Bao, Xiaoze,Nawaz, Shah,Qu, Jingping,Wang, Baomin
, p. 1145 - 1154 (2021/02/16)
An asymmetric [3 + 2] annulation reaction of 4-isothiocyanato pyrazolones with alkynyl ketones in the presence of an organic catalyst derived from a cinchona alkaloid under mild conditions is realized. This protocol provides unprecedented expeditious access to a wide range of optically active spiro[pyrroline-pyrazolones] with various electronic properties in high yields with good to excellent enantioselectivities.
Integrating Reactors and Catalysts through Three-Dimensional Printing: Efficiency and Reusability of an Impregnated Palladium on Silica Monolith in Sonogashira and Suzuki Reactions
Díaz-Marta, Antonio S.,Ya?ez, Susana,Lasorsa, Eliana,Pacheco, Patricia,Tubío, Carmen R.,Rivas, José,Pi?eiro, Yolanda,Gómez, Manuel A. Gonzalez,Amorín, Manuel,Guitián, Francisco,Coelho, Alberto
, p. 1762 - 1771 (2020/02/15)
For this work, an integrated system composed of a polypropylene reactor and a palladium on silica monolithic catalyst was designed and manufactured by 3D-printing. These devices are able to perform solution phase chemistry in a robotic orbital shaker. The capped reactor was obtained in its entirety by 3D-printing, using polypropylene and fused deposition modeling. The monolithic catalyst was also obtained by 3D-printing -robocasting- of a silica support, sintering and subsequent palladium deposition through the wet impregnation method. The catalytic efficiency in Sonogashira or Suzuki reactions as well as the recyclability of the entire system – catalyst+reactor – were studied. The strong electrostatic adsorption (SEA) of the palladium on sintered silica and the reduced mechanical stress produced by the convenient adjustment of the catalyst into the polypropylene reactor makes the catalytic system reusable without significant loss of catalytic activity.
A sustainable access to ynones through laccase/TEMPO-catalyzed metal- and halogen-free aerobic oxidation of propargylic alcohols in aqueous medium
Silva, Alana B.V.,Silva, Emmanuel D.,dos Santos, Alcindo A.,Princival, Jefferson L.
, (2020/02/04)
Tuning laccase/TEMPO-catalyzed aerobic oxidation of secondary propargylic alcohols in aqueous media was accomplished in order to efficiently synthesize ynones. This study led to the formulation of an effective and sustainable catalytic method for the preparation of mono- and bis-substituted ynones compared with traditional oxidative methods.
Regioselective Iron-Catalysed Cross-Coupling Reaction of Aryl Propargylic Bromides and Aryl Grignard Reagents
Manjón-Mata, Inés,Quirós, M. Teresa,Bu?uel, Elena,Cárdenas, Diego J.
supporting information, p. 146 - 151 (2019/12/11)
An iron-catalysed Kumada-type cross-coupling reaction between aryl substituted propargylic bromides and arylmagnesium reagents has been developed. Propargylic coupling products were the main or only outcome, and propargyl/allene regioselectivity was shown to depend on the electronic nature of the substituents on the triple bond of the substrate and on the arylmagnesium halide. Best selectivities were observed when electron donating substituents were present in either reagent. The process is stereoespecific, occurs with configuration inversion and no carbon-based radicals seem to be involved in the mechanism. (Figure presented.).
