“…In fact, starting from E -CA, the EE isomer was the major product in the synthetic mixtures, and there were smaller amounts of the ZE isomer. On the other hand, use of quasipure Z -CA, whose preparation is described in the Supporting Information, led to a mixture of EZ and ZZ compounds. 1 …”
Using a synthetic strategy, based on retention of stereochemistry in the reagent cinnamaldehyde, the four geometrical isomers of 1-(2-anthryl)-4-phenyl-1,3-butadiene were obtained and chromatographically purified. Their structures were established by optical and nuclear magnetic spectrometry and confirmed by their photochemical behavior. Their excited state properties were investigated by stationary and pulsed fluorimetric techniques and by laser flash photolysis. This paper reports the spectral characterization of the four isomers and the photophysical and photochemical parameters obtained by irradiation in a nonpolar solvent at different temperatures. The important contribution of adiabatic pathways in the photoisomerization mechanism and the role of an upper excited singlet state in the relaxation properties are discussed. Indication of the presence of at least two conformers was obtained only when exciting at the extreme red onset region of the absorption spectrum.
“…In fact, starting from E -CA, the EE isomer was the major product in the synthetic mixtures, and there were smaller amounts of the ZE isomer. On the other hand, use of quasipure Z -CA, whose preparation is described in the Supporting Information, led to a mixture of EZ and ZZ compounds. 1 …”
Using a synthetic strategy, based on retention of stereochemistry in the reagent cinnamaldehyde, the four geometrical isomers of 1-(2-anthryl)-4-phenyl-1,3-butadiene were obtained and chromatographically purified. Their structures were established by optical and nuclear magnetic spectrometry and confirmed by their photochemical behavior. Their excited state properties were investigated by stationary and pulsed fluorimetric techniques and by laser flash photolysis. This paper reports the spectral characterization of the four isomers and the photophysical and photochemical parameters obtained by irradiation in a nonpolar solvent at different temperatures. The important contribution of adiabatic pathways in the photoisomerization mechanism and the role of an upper excited singlet state in the relaxation properties are discussed. Indication of the presence of at least two conformers was obtained only when exciting at the extreme red onset region of the absorption spectrum.
“…The most conceptually simple method for the preparation of 1a would involve acylation of phenylacetylene; however, despite various known methods based on this disconnection, the literature was not helpful in presenting an efficient procedure. Easily prepared metal acetylides such as Li, Mg, , and Na suffer from poor yields since the high reactivity of the organometallic reagent leads to some undesired products. Furthermore, using heavy metals such as Cu and Zn affords good results, but these methods required tedious procedures and are not favorable from the environmental point of view.…”
Phenylacetylenic Grignard reagent reacts with acetic
anhydride
under mild conditions to give 4-phenyl-3-butyn-2-one in
high
yield. This method was applicable to a large-scale
synthesis,
and optimized reaction conditions have been investigated.
The aldol condensation takes its name from aldol (3‐hydroxybutanal) a name introduced by Wurtz who first prepared the beta‐hydroxy aldehyde from acetaldehdye in 1872. The aldol condensation includes reactions producing beta‐hydroxy aldehydes or beta‐hydroxy ketones by self condensations or mixed condensations of aldehydes and ketones as well as reactions leading to alpha, beta‐unsaturated aldehydes or alpha,beta‐unsaturated ketones formed by dehydration of intermediate beta‐aldols or beta‐ketals. The Claisen‐Schmidt condensation is most often taken to be the condensation of an aromatic aldehyde or ketone usually in the presence of a basic catalyst. The term aldol condensation has also been applied to many other condensations involving the reaction of an aldehyde or ketone. These condenations are discussed. The present review includes examples that are solely condensation reactions of aldehydes and ketones.
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