15495-23-5Relevant academic research and scientific papers
Pd(II)-catalyzed cascade Wacker-Heck reaction: Chemoselective coupling of two electron-deficient reactants
Silva, Franck,Reiter, Maud,Mills-Webb, Rebecca,Sawicki, Marcin,Klaer, Daniel,Bensel, Nicolas,Wagner, Alain,Gouverneur, Veronique
, p. 8390 - 8394 (2007/10/03)
A novel palladium(II)-catalyzed oxy-carbopalladation process was developed allowing for the orchestrated union of hydroxyynones with ethyl acrylate, two electron-deficient reactants. With β-hydroxy ynones, this cascade Wacker-Heck process gave access to highly functionalized tri- or tetrasubstituted dihydropyranones featuring an unusual dienic system. For diastereomerically pure and for enantioenriched β-hydroxyynones, these reactions proceed without affecting the stereochemical integrity of the existing stereocenters. In addition, tetrasubstituted furanones can be prepared when α-hydroxyynones and ethyl acrylate are used as starting materials. The dihydropyranones and furanones obtained upon cyclization are novel compounds, but structurally related carbohydrate derivatives featuring a similar dienic system have been used as starting materials for the construction of polyannulated products, suggesting that these cascade Pd(II)-mediated oxidative heterocyclizations are of value for various synthetic applications.
Novel and Convenient Routes to Functionalized Alkynyl Ketones from 1-(Benzotriazol-1-yl)propargyl Ethyl Ethers
Katritzky, Alan R.,Lang, Hengyuan
, p. 7612 - 7618 (2007/10/03)
1-(Benzotriazol-1-yl)propargyl ethyl ethers, readily accessible from propargyl aldehyde diethyl acetals and benzotriazole, undergo smooth lithiation at the methine carbon and subsequent reactions with alkyl halides, aldehydes, ketones, imines, esters, trialkylsilyl chlorides, dialkyl carbonates, and isocyanates to yield the corresponding substituted ethers.Hydrolysis of these intermediates under acidic conditions affords a wide variety of alkynyl ketones bearing hydroxy, amino, acyl, trimethylsilyl, alkoxycarbonyl, and (alkylamino)carbonyl substituents at the α-position in good to excellent overall yields.
Coupling and carbonylation of iodoaromatics and terminal alkynes or alkynols catalyzed by a dimeric palladium hydroxide
Delaude,Masdeu,Alper
, p. 1149 - 1151 (2007/10/02)
The palladium(II) complex [(Ph3P)Pd(Ph)(μ-OH)]2 is an effective catalyst for the coupling aud carbonylation of alkynes and iodoarenes to give acetylenic ketones in 63-94% yields. Acetylenic hydroxy ketones were formed using secondary or tertiary alkynols as reactants.
Ring Closure to Ynone Systems: 5- and 6-endo- and -exo-dig Modes
Brennan, Colin M.,Johnson, David C.,McDonnell Peter D.
, p. 957 - 962 (2007/10/02)
The rates of cyclisation of 2-hydroxy-2-methyl-5-arylpent-4-yn-3-ones in trifluoroacetic acid are reported.An approximate ρ value of -4.0 (using ?+) and a kinetic isotope effect KTFA/KTFA-d' of 4.2 are observed, which suggest that the reaction proceeds via rate-limiting triple-bond protonation and does not entail carbonyl protonation along the reaction co-ordinate.The base-catalysed ring closure occurs via the vinilyc carbanion.A similar mechanistic picture appears to be involved in the cyclisation of 1-(2-hydroxyphenyl)-3-arylprop-2-yn-1-ones which yield a mixture of flavone and aurone in base, whilst in acid only the flavone is observed.In contrast with recent theoretical studies, the base-catalysed results appear to conform to Baldwin's original proposal of acute-angle approach of a nucleophile to a triple bond.
