13619-63-1Relevant academic research and scientific papers
Generation and reactivity of ketyl radicals with lignin related structures. On the importance of the ketyl pathway in the photoyellowing of lignin containing pulps and papers
Fabbri, Claudia,Bietti, Massimo,Lanzalunga, Osvaldo
, p. 2720 - 2728 (2007/10/03)
(Chemical Equation Presented) Ketyl radicals with lignin related structures have been generated by means of radiation chemical and photochemical techniques. In the former studies ketyl radicals are produced by reaction of α-carbonyl-β-aryl ether lignin models with the solvated electron produced by pulse radiolysis of an aqueous solution at pH 6.0. The UV-vis spectra of ketyl radicals are characterized by three main absorption bands. The shape and position of these bands slightly change when the spectra are recorded in alkaline solution (pH 11.0) being now assigned to the ketyl radical anions and a pKa = 9.5 is determined for the 1-(3,4,5-trimethoxyphenyl)-2- phenoxyethanol-1-yl radical. Decay rates of ketyl radicals are found to be dose dependent and, at low doses, lie in the range (1.7-2.7) × 103 s-1. In the presence of oxygen a fast decay of the ketyl radicals is observed (k2 = 1.8-2.7 × 109 M-1 s -1) that is accompanied by the formation of stable products, i.e., the starting ketones. In the photochemical studies ketyl radicals have been produced by charge-transfer (CT) photoactivation of the electron donor-acceptor salts of methyl viologen (MV2+) with α-hydroxy-α- phenoxymethylaryl acetates. This process leads to the instantaneous formation of the reduced acceptor (methyl viologen radical cation, MV+?), as is clearly shown in a laser flash photolysis experiment by the two absorption bands centered at 390 and 605 nm, and an acyloxyl radical [ArC(CO 2?)(OH)CH2(OC6H5)], which undergoes a very fast decarboxylation with formation of the ketyl radicals. Steady-state photoirradiation of the CT ion pairs indicates that 1-aryl-2-phenoxyethanones are formed as primary photoproducts by oxidation of ketyl radicals by MV2+ (under argon) or by molecular oxygen. Small amounts of acetophenones are formed by further photolysis of 1-aryl-2-phenoxyethanones and not by β-fragmentation of the ketyl radicals. The high reactivity of ketyl radicals with oxygen coupled with the low rates of β-fragmentation of the same species have an important bearing in the context of the photoyellowing of lignin containing pulps and papers.
Synthesis and Antiestrogenic Activity of Diaryl Thioether Derivatives
Poirier, Donald,Auger, Serge,Merand, Yves,Simard, Jacques,Labrie, Fernand
, p. 1115 - 1125 (2007/10/02)
The reaction of 1,2-diarylethanol and mercapto side chain catalyzed by ZnI2 was used as a key step in the short (three to five steps) and efficient synthesis of 17 diaryl thioether derivatives.Several of these compounds contain a methyl butyl amide chain and an hydroxyaryl moiety, respectively, for antiestrogenic activity and binding affinity on estrogen receptor.No binding affinity for crude cytosolic preparation of the estrogen receptor was observed for compounds without phenolic group, while a low affinity (0.01-0.05percent) was measured for mono- or diphenol derivatives.Like the pure steroidal antiestrogen EM-139, these novel nonsteroidal compounds did not exert any stimulatory effect on cell proliferation of (ER+) ZR-75-1 human breast cancer cells and partially reversed the amplitude of the stimulatory effect induced by estradiol on this (ER+) cell line.No proliferative or antiproliferative effect on (ER-) MDA-MB-231 human breast cancer cells was also observed for three of these compounds (39-41).Among the newly synthesized nonsteroidal compounds, the thioether derivative 41 (N-butyl-N-methyl-13,14-bis(4'-hydroxyphenyl)-12-thiatetradecanamide), with a long methylbutylalkanamide side chain and a diphenolic nucleus, was selected as the best antiestrogenic compound.However, this compound was 100-fold less antiestrogenic in (ER+) ZR-75-1 cells than the steroidal antiestrogen EM-139.
Synthesis of 3-aryl-1-(4-methoxyphenyl)-2--2-propen-1-ones and benzopyran derivatives
Verma, Braham S.,Dhindsa, Kuldip Singh,Sangwan, Naresh K.
, p. 239 - 243 (2007/10/02)
Acylation of anisole (5) or m-methoxyphenol (6) with arylacetic acid (7 or 8) gives the corresponding deoxybenzoins (9-12) along with minor isomeric product 13 in one case.Acetylation of 4-hydroxy-4'-methoxydeoxybenzoin (10) with acetic anhydride in pyridine or its alkylation with N-(2-chloroethyl)diethylammonium/pyrrolidinium chloride furnishes the corresponding deoxybenzoin derivatives (14-16).Condensation of 9, 11, 15 and 16 with araldehydes affords the corresponding title compounds 2-propen-1-ones (17, 19 and 21-23). 1-(2-Hydroxy-4-methoxyphenyl)-2,3-diphenyl-2-propen-1-one (19) is isomerized using silica gel or hydrochloric acid to 2,3-trans-2,3-dihydro-7-methoxy-2,3-diphenyl-4H-1-benzopyran-4-one (24) which on sodium borohydride reduction provides a mixture of isomeric benzopyranols (25).Dehydration of 25 gives 7-methoxy-2,3-diphenyl-2H/4H-1-benzopyran (27).The isomeric 7-methoxy-2,4-diphenyl-2H/4H-1-benzopyran (28) is prepared by the reaction of 2,3-dihydro-7-methoxy-2-phenyl-4H-1-benzopyran-4-one (26) with phenylmagnesium bromide.Condensation of 11 with 7 in acetic anhydride/triethylamine furnishes 4-benzyl-7-methoxy-3-phenyl-2H-1-benzopyran-2-one (29).
PHOTOCHEMISTRY OF α-PHENOXY-p-METHOXYACETOPHENONE
Netto-Ferreira, J. C.,Scaiano, J. C.
, p. 443 - 446 (2007/10/02)
The triplet state of the title compound decays by a competition of β-phenyl quenching and β-cleavage leading to CH3OC6H4COCH2. and phenoxyl radicals.The latter process occurs with a quantum yield of 0.020.
