65564-83-2Relevant articles and documents
A synthesis of ynolates via the cleavage of ester dianions
Shindo, Mitsuru
, p. 4433 - 4436 (1997)
A new method for ynolate synthesis via the cleavage of ester dianions has been developed. The key intermediates, ester dianions, generated from α-bromocarboxylic acid ester enolates via lithium-halogen exchange turned out to be so labile that they were cleaved rapidly to give ynolates.
Highly Regio- And Enantioselective Reductive Coupling of Alkynes and Aldehydes via Photoredox Cobalt Dual Catalysis
Li, Yan-Lin,Zhang, Shi-Qi,Chen, Jie,Xia, Ji-Bao
, p. 7306 - 7313 (2021/05/26)
A Co-catalyzed highly regio- and enantioselective reductive coupling of alkynes and aldehydes has been developed under visible light photoredox dual catalysis. A variety of enantioenriched allylic alcohols have been obtained by using unsymmetrical internal alkynes and commercially available catalyst, chiral ligand, and reagents. It is noteworthy that this approach has considerable advantages, such as excellent regio- (>95:5 for >40 examples), stereo- (up to >95:5 E/Z), and enantioselectivity (92-99% ee, >35 examples) control, mild reaction conditions, broad substrate scope, and good functional group compatibility, making it a great improvement to enantioselective alkyne-aldehyde reductive coupling reactions.
H-*BEA Zeolite-Catalyzed Nucleophilic Substitution in Allyl Alcohols Using Sulfonamides, Amides, and Anilines
Aoki, Shunsuke,Fujii, Takeshi,Morita, Sachiko,Nishida, Ryo,Ohtsuki, Akimichi,Okumura, Kazu
, (2020/07/24)
Herein, we report a novel zeolite-catalyzed nucleophilic substitution in allyl alcohols. The product yield was improved upon the addition of NaOTf (0.05 mol-percent) using the studied zeolites. The highest yields were observed using H-*BEA(Si/Al2 = 40)/NaOTf. The scope of the reaction with respect to the nucleophile was examined using 1,3-diphenylprop-2-ene-1-ol as a model substrate under optimized reaction conditions. p-Substituted aryl sulfonamides bearing electron-rich or electron-deficient substituents, alkyl sulfonamides, and heteroaryl sulfonamides undergo the amidation reaction to produce their corresponding allyl sulfonamides in good yield. Amides and anilines exhibited low activity under the optimized conditions, however, performing the reaction at 90 °C produced the target product. The scope of the allyl alcohol was investigated using p-toluenesulfonamide as the nucleophile and the reaction proceeded with a variety of allylic alcohols. To probe the practical utility of the H-*BEA-catalyzed amidation reaction, a gram-scale reaction was performed using 1.01 g (4.8 mmol) of allyl alcohol, which afforded the target product in 88 percent yield.
Nickel-Catalyzed Reductive Coupling of Aldehydes with Alkynes Mediated by Alcohol?
Zheng, Yan-Long,Ye, Mengchun
supporting information, p. 489 - 493 (2020/04/23)
A nickel-catalyzed reductive coupling of aldehydes with alkynes using 1-phenylethanol as reducing agent has been developed. The key achievement of this work is that we demonstrate environmentally benign 1-phenylethanol can serve as a viable alternative reducing agent to Et3B, ZnEt2 and R3SiH for the nickel-catalyzed reductive coupling reaction of aldehyde and alkynes.
Investigation of substituent effects on the selectivity of 4π-electrocyclization of 1,3-diarylallylic cations for the formation of highly substituted indenes
Smith, Chris D.,Rosocha, Gregory,Mui, Leo,Batey, Robert A.
supporting information; experimental part, p. 4716 - 4727 (2010/09/05)
(Figure Presented) Differentially substituted 1,3-diaryl-substituted allylic cations generated by ionization of the corresponding allylic alcohols in the presence of a Lewis acid undergo chemoselective and regioselective electrocyclization reactions to generate 1-aryl-1H-indenes. Electrocyclization only occurs for allylic cations bearing a 2-substituent, with 2-ester and 2-alkyl substituents both tolerated. In general, the presence of electron-withdrawing substituents deactivates the ring and disfavors cyclization. In contrast, the selectivity of cyclization of systems containing electron-donating substituents depends on the nature and position of the electron-donating group. Electron-donating substituents at the meta position particularly favor cyclization. There was no obvious correlation of cyclization selectivity with calculated electron densities as has been suggested for electrophilic aromatic substitution reactions. However, the calculated selectivities determined by a gas-phase (B3LYP/6-31G* + ZPVE) comparison of the relative rates of cyclization were in remarkably good agreement with the observed selectivities. Calculated transition-state structures for cyclization are consistent with a cationic π4a conrotatory electrocyclization mechanism. In some cases involving more electron-deficient systems, the initially formed 1H-indene underwent subsequent alkene isomerization to the 3H-indene. In one example, an unusual dimerization reaction occurred to give a cyclopenta[a]indene via an unusual formal cationic 2π+2π cycloaddition of the allylic cation with the intermediate indene.
Interesting nickel-catalyzed 1,2-addition to α, β-unsaturated aldehydes with arylborates
Sakurai, Fumie,Kondo, Kazuhiro,Aoyama, Toyohiko
experimental part, p. 511 - 512 (2009/12/05)
Ni-Et-Duphos-catalyzed 1,2-addition of potassium aryltrifluoroborates to α, β-unsaturated aldehydes is described.
Axial coordination of NHC ligands on dirhodium(II) complexes: Generation of a new family of catalysts
Trindade, Alexandre F.,Gois, Pedro M. P.,Veiros, Luis F.,Andre, Vania,Duarte, M. Teresa,Afonso, Carlos A. M.,Caddick, Stephen,Cloke, F. Geoffrey N.
, p. 4076 - 4086 (2008/09/20)
(Chemical Equation Presented) An efficient new methodology for the arylation of aldehydes is disclosed which uses dirhodium(II) catalysts and N-heterocyclic carbene (NHC) ligands. Complexes of Rh2(OAc) 4 with one and two NHCs attached on the axial positions were successfully isolated, fully characterized, and used as catalysts in the reaction. The saturated monocomplex ((NHC 5)Rh2(OAc)4) 31 was shown to be the most active catalyst and was particularly efficient in the arylation of alkyl aldehydes. DFT calculations support participation of complexes with one axial NHC in the reaction as the catalysts active species and indicate that hydrogen bonds involving dirhodium unit, reactants, and solvent (alcohol) play an important role on the reaction mechanism.
Tandem addition β-lithiation - Alkylation sequence on α,β-unsaturated aldehydes
Nudelman,Garcia
, p. 1387 - 1394 (2007/10/03)
A tandem reaction between (E)-cinnamaldehyde, 1a, and phenyllithium affording β-substituted dihydrochalcones was recently reported. NMR spectroscopic studies on the reaction mixture, as well as isotopic exchange reactions and trapping of two intermediates, provide clues on the several mechanistic steps of this new reaction. Extended studies revealed that β-alkyl-substituted α,β-unsaturated aldehydes and aliphatic lithium reagents did not afford good yields of the tandem reaction products, while aromatic lithium reagents gave good results. The aggregation features of the aryllithium reagents and the extended charged delocalization effects are considered to promote β-selectivity. This approach provides a convenient route for the synthesis of a wide variety of β-alkyl-substituted dihydrochalcones.
Highly selective catalytic intermolecular reductive coupling of alkynes and aldehydes
Huang, Wei-Sheng,Chan, Johann,Jamison, Timothy F.
, p. 4221 - 4223 (2007/10/03)
(aquation presented) Alkynes (internal and terminal) and aldehydes (aromatic and aliphatic) are reductively coupled in a single catalytic reaction to yield di- and trisubstituted allylic alcohols with high stereoselectivity and regioselectivity. In most cases, a 1:1 ratio of alkyne to aldehyde is sufficient for efficient coupling. The yield and regioselectivity are strongly dependent on the phosphine ligand, but the allylic alcohols formed are invariably the products of cis addition to the alkyne.
Novel synthesis of ynolates via the cleavage of ester dianions: α-bromo and α,α-dibromo esters as precursors
Shindo, Mitsuru,Sato, Yusuke,Shishido, Kozo
, p. 2411 - 2422 (2007/10/03)
Ynolates have been synthesized via the thermally-induced cleavage of ester dianions. The key intermediates, ester dianions, were generated from α-bromocarboxylic acid ester enolates via lithium halogen exchange. α,α-Dibromocarboxylic acid ester also gives lithium amide free ynolates by addition of tert-BuLi. The reactions of ynolates, generated by this novel and convenient method, with aldehydes to give β-lactons are discussed.
