13466-40-5Relevant articles and documents
Electronic absorption and fluorescence properties of 2,5-diarylidene-cyclopentanones
Connors, Robert E.,Ucak-Astarlioglu, Mine G.
, p. 7684 - 7691 (2003)
Spectroscopic properties for a series of 2,5-diarylidene-cyclopentanones are reported. Electronic absorption and fluorescence spectra have been measured for the all-E configurations of 2,5-dibenzylidene-cyclopentanone (1), 2,5-bis-(3-phenyl-allylidene)-cyclopentanone (2), and 2,5-bis-(5-phenyl-penta-2,4-dienylidene)-cyclopentanone (3). The absorption spectra have been assigned with the aid of INDO/S calculations. Molecular structures used for the INDO/S calculations were computed with the PM3 Hamiltonian. Agreement between absorption spectra obtained in cyclohexane at room temperature and the theoretical predictions is good. For 1, 2, and 3 the general features of the spectra are similar. The transition to S1 (weak) is assigned as n → π* (A2 ← A1), to S2 (strong) as π → π* (B2 ← A1), and to S3 (moderate) as π → π* (A1 ← A1). The energy gap between S1 and S2 is seen to decrease as the length of the polyene chain increases in going from 1 to 3. Fluorescence is not observed for 1 in any of the solvents studied (protic and aprotic). Fluorescence is observed for 2 in protic solvents only. For 3, fluorescence is observed in a number of protic and aprotic solvents. Solvents which are able to induce fluorescence are believed to do so by inverting the order of 1(nπ*) and 1(ππ*) states. The influence of hydrogen bonding on the excitation spectra of 2 and 3 is discussed. Solvent-induced shifts in the absorption and fluorescence spectra of 3 in combination with the PM3 calculated ground-state dipole moment (2.8 D) are used to determine the excited-state dipole moment of 3 (6.4 D/protic solvents; 6.6 D/aprotic solvents). Fluorescence quantum yields in different solvents for 3 vary as the fluorescence maxima shift in these solvents, going through a maximum in the mid-frequency range. The variation in quantum yields with different solvents is primarily attributed to changes in the nonradiative rate of decay from S1. Excitation, polarized excitation, and fluorescence spectra have been measured for 2 and 3 at 77 K in ethanol/ methanol glass. Vibronic features not observed in the broad spectra obtained in alcohols at room temperature become clearly resolved at 77 K. Evidence is provided that indicates that 2 and 3 undergo excited-state proton-transfer reactions in acetic acid at room temperature.
Addition of carbon nucleophiles to aldehyde tosylhydrazones of aromatic and heteroaromatic-compounds: Total synthesis of piperine and its analogs
Chandrasekhar,Venkat Reddy,Srinivasa Reddy,Ramarao
, p. 2667 - 2670 (2000)
Addition of carbon nucleophiles to aldehyde tosylhydrazones of aromatic and heteroaromatic compounds is reported. New observations have been made wherein alkylative reduction is observed in some cases whereas alkylative fragmentation is noticed in others. These findings are exploited in the synthesis of the useful alkaloid piperine and its analogs. (C) 2000 Elsevier Science Ltd.
Derives silyles issus d'aldimines α,β-insaturees: preparations et applications en synthese
Bellassoued, M.,Majidi, A.
, p. C7 - C8 (1993)
The preparation of silylated N-tert-butyl α,β-unsaturated aldimines is reported.The disilylated reagent 3a derived from crotonaldimine is used for the conversion of aromatic aldehydes into conjugated dienals in one-pot reaction.
Aldehydes α-silyles: preparation et properties nouvelles
Duhamel, L.,Gralak, J.,Ngono, B.
, p. C4 - C6 (1989)
t-Butyldimethylsilyl acetaldehyde (3) is obtained from the hydrolysis of the (Z)-β-silylenoxysilane (2), prepared from (Z)-1-bromo-2-(trimethylsiloxy)ethylene by reaction with t-butyllithium followed by condensation with t-butyldimethylsilyl triflate.The lithium enolate of aldehyde 3 is prepared direct by reaction with lithium diisopropylamide or lithium hexamethyldisilazane; its condensation with trimethylchlorosilane leads to the (E)-β-silylenoxysilane (2) and with aldehydes, to α,β-ethylenic aldehydes (4).
Application of (2E,4E)-5-bromo-2,4-pentadienal in palladium catalyzed cross-coupling: Easy access to (2E,4E)-2,4-dienals
Vicart, Nicolas,Castet-Caillabet, Dominique,Ramondenc, Yvan,Plé, Gérard,Duhamel, Lucette
, p. 411 - 412 (1998)
Palladium catalyzed cross-coupling reactions of (2E,4E)-5-bromo-2,4-pentadienal 1 with organozinc reagents gives an easy access to the corresponding (2E,4E)-2,4-dienals. The improved preparation of all trans 1 by isomerization of its (2E,4Z) isomer is reported.
Sato et al.
, p. 8281 (1976)
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Yamamoto,K. et al.
, p. 713 - 716 (1979)
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Method for preparing olefine aldehyde by catalyzing terminal alkyne or terminal conjugated eneyne and diphosphine ligand used in method
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Paragraph 0168-0171, (2021/05/29)
The invention discloses a method for preparing olefine aldehyde by catalyzing terminal alkyne or terminal conjugated eneyne and a diphosphine ligand used in the method. According to the invention, indole-substituted phosphoramidite diphosphine ligand which is stable in air and insensitive to light is synthesized by utilizing a continuous one-pot method, and the indole-substituted phosphoramidite diphosphine ligand and a rhodium catalyst are used for jointly catalyzing to successfully achieve a hydroformylation reaction of aromatic terminal alkyne and terminal conjugated eneyne under the condition of synthesis gas for the first time, so that an olefine aldehyde structure compound can be rapidly and massively prepared, and particularly, a polyolefine aldehyde structure compound which is more difficult to synthesize in the prior art can be easily prepared and synthesized, and a novel method is provided for synthesis and modification of drug molecules, intermediates and chemical products.
Selective Rhodium-Catalyzed Hydroformylation of Terminal Arylalkynes and Conjugated Enynes to (Poly)enals Enabled by a π-Acceptor Biphosphoramidite Ligand
Zhao, Jiangui,Zheng, Xueli,Tao, Shaokun,Zhu, Yuxin,Yi, Jiwei,Tang, Songbai,Li, Ruixiang,Chen, Hua,Fu, Haiyan,Yuan, Maolin
, p. 6067 - 6072 (2021/08/16)
The hydroformylation of terminal arylalkynes and enynes offers a straightforward synthetic route to the valuable (poly)enals. However, the hydroformylation of terminal alkynes has remained a long-standing challenge. Herein, an efficient and selective Rh-catalyzed hydroformylation of terminal arylalkynes and conjugated enynes has been achieved by using a new stable biphosphoramidite ligand with strong π-acceptor capacity, which affords various important E-(poly)enals in good yields with excellent chemo- and regioselectivity at low temperatures and low syngas pressures.