- Palladium-tetraphosphine complex catalysed heck reaction of vinyl bromides with alkenes: A powerful access to conjugated dienes
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A wide variety of 1,3-dienes have been prepared by the Heck vinylation of vinyl bromides using [Pd(η3-C3H5)Cl] 2/cis,cis,cis-1,2,3,4-tetrakis[(diphenylphosphino)methyl] cyclopentane (Tedicyp) as the catalyst precursor. Both α- and β-substituted vinyl bromides undergo the Heck reaction with functionalised alkenes such as acrylates, enones, styrenes or a vinyl sulfone, and also with nonfunctionalised alkenes such as dec-1-ene, leading stereoselectively, in most cases, to the corresponding E- or E,E-1,3-dienes in good yields. Furthermore, this catalyst can be used at low loading for several reactions. Georg Thieme Verlag Stuttgart.
- Lemhadri, Mhamed,Battace, Ahmed,Berthiol, Florian,Zair, Touriya,Doucet, Henri,Santelli, Maurice
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p. 1142 - 1152
(2008/12/22)
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- Heck reaction of vinyl bromides with alkenes in the presence of a tetraphosphine/palladium catalyst
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Through the use of [PdCl(C3H5)]2- cis,cis,cis-1,2,3,4-tetrakis(diphenylphosphinomethyl)cyclopentane as a catalyst, a range of vinyl bromides undergo Heck reaction with a wide variety of alkenes leading selectively to the corresponding 1,3-dienes in good yields. Furthermore, it can be used at low loading even for reactions of sterically hindered vinyl bromides.
- Berthiol, Florian,Doucet, Henri,Santelli, Maurice
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p. 841 - 844
(2007/10/03)
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- Synthesis and evaluation of a series of 1,4-diarylbutadienes for anticoccidial activity
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During the course of a collaborative screening program, a set of 1-phenyl-4-pyridyl-butadienes was found to exhibit in vitro activity against Eimeria tenella in a cell-based assay. Activity was dependent on the chain length and degree of unsaturation of t
- Gage, Jennifer L.,Kirst, Herbert A.,O'Neil, Deirdre,David, Bridget A.,Smith II, Charles K.,Naylor, Sharon A.
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p. 4083 - 4091
(2007/10/03)
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- Photoisomerization mechanisms and photoselectivity of the stereoisomers of 1-(pyrid-n-yl),4-phenylbuta-1,3-diene
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The positional isomers of 1-(pyrid-n-yl),4-phenylbuta-1,3-diene (n = 2, 3 and 4) have been synthesized and characterized by spectrometric techniques. All the four expected stereoisomers (EE, EZ, ZE and ZZ) were prepared for n = 2 while only three and two geometrical isomers were obtained for the positional isomers with n = 3 and 4, respectively. Their excited state properties were investigated by stationary and pulsed fluorimetric techniques and by laser flash photolysis. This paper describes the photochemical behaviour under direct and triplet sensitized excitation. The selective formation of photoproducts and the role of diabatic/adiabatic mechanisms are reported and compared with the results on the direct photoisomerization of the EE and ZE isomers in the singlet manifold described in a previous paper (G. Bartocci, G. Galiazzo, U. Mazzucato and A. Spalletti, Phys. Chem. Chem. Phys., 2001, 3, 379-386).
- Bartocci,Galiazzo,Latterini,Marri,Mazzucato,Spalletti
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p. 2911 - 2916
(2007/10/03)
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- Photophysics and photochemistry of the EE and ZE isomers of 1-(n-pyridyl)-4-phenyl-1,3-butadiene (n = 2, 3 and 4)
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The positional isomers of 1-(n-pyridyl)-4-phenyl-1,3-butadiene (n = 2, 3 and 4) have been synthesized in the EE and ZE geometries by common routes and characterized by spectrometric techniques. Their excited state properties were investigated by stationary and pulsed fluorimetric techniques and by laser flash photolysis. This paper reports the spectral, photophysical and photochemical behaviour of the EE and ZE isomers in a non-polar solvent. The photoisomerization proceeds through singlet, diabatic and/or adiabatic mechanisms with generally low quantum yield, owing to the role of internal conversion (markedly more important for n = 2). The role of intramolecular hydrogen bonds on the excited state properties of the ZE isomer of the 2-pyridyl derivative is particularly described.
- Bartocci,Galiazzo,Mazzucato,Spalletti
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p. 379 - 386
(2007/10/03)
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