57081-00-2Relevant academic research and scientific papers
Palladium-Catalyzed Aerobic Oxidative Carbonylation of C–H Bonds in Phenols for the Synthesis of p-Hydroxybenzoates
Gaikwad, Vinayak V.,Bhanage, Bhalchandra M.
, p. 2877 - 2881 (2018/06/21)
This work reports the synthesis of p-hydroxybenzoates directly from phenols by oxidative carbonylation of phenolic C–H bonds, proceding through oxidative iodination. The developed methodology is efficient and economically attractive because phenols are cheap and easily available starting materials. This one-pot strategy was expediently applied to the synthesis of a variety of p-hydroxybenzoates by utilizing simple primary and secondary alcohols with different phenols under mild reaction conditions. Advantageously, the procedure has no need for co-catalysts, co-solvents or external ligands. The utilization of molecular oxygen as a terminal oxidant for C–H bond oxidation represents an additional benefit.
Copper-catalyzed oxidative aromatization of 2-cyclohexen-1-ones to phenols in the presence of catalytic hydrogen bromide under molecular oxygen
Kikushima, Kotaro,Nishina, Yuta
, p. 20150 - 20156 (2013/11/06)
Catalytic oxidative aromatization has been achieved using 2-cyclohexen-1-ones to obtain phenol derivatives in the presence of a catalytic amount of copper salt and aqueous HBr under molecular oxygen. The amount of HBr was successfully reduced to a catalytic quantity, and the other additive such as a ligand and an oxidant as well as inert conditions were unnecessary. Various mono-, di-, and trisubstituted phenols with substituents at the desired positions could be synthesized under cheap and simple conditions. An oxidative aromatization/bromination sequence was also demonstrated to obtain bromophenols with excess HBr. The Royal Society of Chemistry 2013.
Aerobic oxidative heck/dehydrogenation reactions of cyclohexenones: Efficient access to meta-substituted phenols
Izawa, Yusuke,Zheng, Changwu,Stahl, Shannon S.
supporting information, p. 3672 - 3675 (2013/04/23)
Jockeying for the (meta)position: A new dicationic palladium(II) catalyst, employing a 6,6′-dimethyl-2,2′-bipyridine ligand, promotes both the aerobic oxidative Heck coupling and dehydrogenation reactions of cyclohexenones. These reactions may be combined in a one-pot sequence to enable the straightforward synthesis of meta-substituted phenols (see scheme). Copyright
One-pot catalysis of dehydrogenation of cyclohexanones to phenols and oxidative Heck coupling: Expedient synthesis of coumarins
Kim, Donghee,Min, Minsik,Hong, Sungwoo
supporting information, p. 4021 - 4023 (2013/07/26)
One-pot reactions leading to highly functionalized coumarins have been developed via a Pd(ii)-catalyzed dehydrogenation-oxidative Heck-cyclization process.
Palladium-catalyzed aerobic dehydrogenation of substituted cyclohexanones to phenols
Izawa, Yusuke,Pun, Doris,Stahl, Shannon S.
scheme or table, p. 209 - 213 (2012/06/01)
Aromatic molecules are key constituents of many pharmaceuticals, electronic materials, and commodity plastics. The utility of these molecules directly reflects the identity and pattern of substituents on the aromatic ring. Here, we report a palladium(II) catalyst system, incorporating an unconventional ortho-dimethylaminopyridine ligand, for the conversion of substituted cyclohexanones to the corresponding phenols. The reaction proceeds via successive dehydrogenation of two saturated carbon-carbon bonds of the six-membered ring and uses molecular oxygen as the hydrogen acceptor. This reactivity demonstrates a versatile and efficient strategy for the synthesis of substituted aromatic molecules with fundamentally different selectivity constraints from the numerous known synthetic methods that rely on substitution of a preexisting aromatic ring.
Vanadium-catalyzed oxidative aromatization of 2-cyclohexenones under molecular oxygen
Moriuchi, Toshiyuki,Kikushima, Kotaro,Kajikawa, Tomomi,Hirao, Toshikazu
supporting information; experimental part, p. 7385 - 7387 (2010/01/18)
An efficient catalytic oxidative aromatization of 2-cyclohexenones was achieved by a combination of a commercially available inexpensive ligand-free vanadium catalyst, a bromide source, and an acid under atmospheric oxygen to afford the corresponding phenol derivatives. This catalytic oxidative aromatization proceeded even under air. Furthermore, a gram-scale reaction was performed successfully.
Towards room temperature biaxial nematics
Cooper, Lori L.,Samulski, Edward T.,Scharrer, Eric
experimental part, p. 2031673 - 2171687 (2010/07/20)
A series of new liquid crystalline compounds based on the 2,5-bis-(p-hydroxyphenyl)-1,3,4-oxadiazole (ODBP) core was synthesized in an effort to access the biaxial nematic phase at low temperatures. Derivatives with secondary terminal alkoxy groups and de
Photochemistry of bicyclo[2.2.2]oct-7-ene-2,5-diones and the corresponding 5-hydroxyimino and 5-methylene derivatives
Yang, Ming-Shyong,Lu, Shyue-Sheng,Rao, Chitneni Prasad,Tsai, Yow-Fu,Liao, Chun-Chen
, p. 6543 - 6553 (2007/10/03)
Synthesis and photochemistry of several title compounds 1-3 containing multiple chromophoric systems are described. The Diels-Alder reactions of 2,6,6-trimethylcyclohexa-2,4-dienone (5) with acetylenes 6a-d provided the adducts 7a-d, which upon hydrolysis furnished the desired bicyclo[2.2.2]octenediones 1a-d. Oximes 2a-d were prepared from diones 1a-d by treatment with hydroxylamine hydrochloride in pyridine. 5-Methylenebicyclo[2.2.2]oct-7-en-2-ones 3a-d were obtained via chemoselective Wittig reaction of the corresponding diones 1a-d. Bicyclo[2.2.2]-octenediones 1a-c underwent chemoselective oxa-di-π-methane rearrangement under sensitized conditions and suffered formal ketene extrusion upon direct irradiation. Direct irradiation of ld afforded 11d via formal ketene extrusion but under sensitization it remained unchanged. Oximes 2a-d suffered ketene extrusion upon direct irradiation and E/Z isomerization under sensitized conditions. On the other hand, 5-methylenebicyclo[2.2.2]oct-7-en-2-ones 3a-d generally underwent 1,3-acyl shift. The plausible courses of all these photochemical processes are discussed.
Aromatization of Cyclohexenones with Iodine/sodium alkoxide. A Regioselective synthesis of 2-Iodophenols
Hegde, Shridhar G.,Kassim, Amude M.,Ingrum, April I.
, p. 8395 - 8398 (2007/10/02)
Aromatizations of a wide variety of easily accessible 2-cyclohexenone-4-carboxylates with iodine and sodium ethoxide give the corresponding 2-iodophenols in good yield and high regioselectivity.
Synthesis of 4-Hydroxy-2-methylbenzoic Acid and Its Higher Homologues
Sen, P. K.,Pal, Panchanan,Goswami, Shyamaprosad,Chattopadhyay, Gautam
, p. 679 - 682 (2007/10/02)
Synthesis of 4-hydroxy-2-methylbenzoic acid (1a) and its higher homologues such as 4-hydroxy-2-methylphenylacetic acid (1b), 3-(4-hydroxy-2-methylphenyl)propanoic acid (1c) and 4-(4-hydroxy-2-methylphenyl)butanoic acid (1d) are described.
