494-13-3Relevant academic research and scientific papers
Scope and Mechanism of the Ruthenium-Catalyzed Dehydrative C-H Coupling of Phenols with α,β-Unsaturated Carbonyl Compounds: Expedient Synthesis of Chromene and Benzoxacyclic Derivatives
Mokar, Bhanudas Dattatray,Yi, Chae S.
supporting information, p. 4625 - 4632 (2019/12/24)
Chromene and benzoxacyclic derivatives were efficiently synthesized from the ruthenium-catalyzed dehydrative C-H coupling reaction of phenols with α,β-unsaturated carbonyl compounds. The cationic ruthenium-hydride complex was found to be an effective catalyst for the coupling and annulation of phenols with enals to form chromene products. The coupling of phenols with linear enones afforded 2,4-disubstituted chromene derivatives, whereas the analogous coupling with cyclic enones yielded 9-hydroxybenzoxazole products. The reaction of 3,5-dimethoxyphenol with PhCH=CHCDO resulted in the chromene product with a significant H/D exchange to both benzylic and vinyl positions. The most significant carbon isotope effect from the coupling of 3,5-dimethoxyphenol with 4-methoxycinnamaldehyde was observed on the α-olefinic carbon of the chromene product (C(2) = 1.067). A Hammett plot from the coupling of 3,5-dimethoxyphenol with para-substituted p-X-C6H4CH=CHCHO displayed a linear correlation, with a strong promotional effect by an electron-withdrawing group (ρ = +1.5; X = OCH3, CH3, H, F, Cl). Several biologically active chromenone derivatives were synthesized by using the catalytic coupling method. The catalytic method provides an expedient synthetic protocol for the coupling of phenols with α,β-unsaturated carbonyl compounds without employing reactive reagents or forming any wasteful byproducts.
Dioxomolybdenum Complexes as Excellent Catalysts for the Deoxygenation of Aryl Ketones to Aryl Alkenes
Fernandes, Tiago A.,Fernandes, Ana C.
, p. 3503 - 3507 (2015/11/10)
This work describes a new methodology for the selective deoxygenation of aryl ketones to the corresponding aryl alkenes catalyzed by dioxomolybdenum complexes using silanes as reducing agents. The best results were obtained with the system PhSiH3/MoO2Cl2(H2O)2 (5-10 mol %), which was very efficient for the deoxygenation of a large variety of aryl ketones to alkenes in excellent yields. This new methodology has the advantages of using an inexpensive, environmentally friendly, easily prepared, and air-stable catalyst in ether solution.
Ring-closing metathesis as a new methodology for the synthesis of monomeric flavonoids and neoflavonoids
Miller, Bradley J.,Pieterse, Tanya,Marais, Charlene,Bezuidenhoudt, Barend C.B.
, p. 4708 - 4710 (2012/09/21)
Basic flavonoid (flavene) and neoflavonoid (neoflavene) skeletons were successfully synthesized using ring-closing metathesis, showing that this methodology can be used as a central synthetic tool for the synthesis of at least two of the three basic flavonoid classes.
Enantioselective synthesis of chromanes by iridium-catalyzed asymmetric hydrogenation of 4H-chromenes
Valla, Carine,Baeza, Alejandro,Menges, Frederik,Pfaltz, Andreas
body text, p. 3167 - 3171 (2009/06/17)
Iridium complexes of chiral oxazoline-based P,N-ligands proved to be efficient catalysts for the enantioselective hydrogenation of 2-aryl- and 2-alkyl-4H-chromenes. The best results were obtained with a ligand derived from threonine (ThrePHOX), which induced ee values of 95% to >99% in the hydrogenation of 2-methyl-, 2-cyclohexyl- and various 2-aryl-substituted chromenes. Georg Thieme Verlag Stuttgart.
Kinetics of the reactions of flavylium ions with π-nucleophiles
Fichtner, Claudia,Remennikov, Grigoriy,Mayr, Herbert
, p. 4451 - 4456 (2007/10/03)
The kinetics of the reactions of the flavylium ion 1a and the 4′-methoxyflavylium ion 1b with various π-nucleophiles and tributylstannane were investigated photometrically in dichloromethane. Electrophilicity parameters E(1a) = -3.46 and E(1b) = -4.96 were derived from the equation log k (20°C) = s(E + N); these allow the prediction of potential reaction partners of the flavylium ions 1a and 1b.
Reactions of Flav-2-enes and Flav-2-en-4-ones (Flavones)
Bird, T. Geoffrey C.,Brown, Ben R.,Stuart, Ian A.,Tyrrell, William R.
, p. 1831 - 1846 (2007/10/02)
Flav-2-enes, flavones, and 3-alkyl ethers of flavonols add alcohols and carboxylic acids in the presence of N-bromosuccinimide to give 2-alkoxy- and 2-acyloxy-3-bromoflavans which provide routes to cis-3-bromoflavans by reduction and to 3,4-diols by elimination and reaction with osmium tetraoxide.The 2-acyloxyflavans react with alcohols yielding 2-alkoxyflavans.Flavonols react with N-bromosuccinimide and alcohols to give bromine-free hemiacetals, the known 2,3-dialkoxy-3-hydroxyflavanones.
