223575-93-7Relevant academic research and scientific papers
Regio- and Chemoselective Kumada-Tamao-Corriu Reaction of Aryl Alkyl Ethers Catalyzed by Chromium under Mild Conditions
Cong, Xuefeng,Tang, Huarong,Zeng, Xiaoming
supporting information, p. 14367 - 14372 (2015/12/01)
Acting as an environmentally benign synthetic tool, the cross-coupling reactions with aryl ethers via C-O bond activation have attracted broad interest. However, the functionalizations of C-O bonds are mainly limited to nickel catalysis, and selectivity has long been a prominent challenge when several C-O bonds are present in the one molecule. We report here the first chromium-catalyzed selective cross-coupling reactions of aryl ethers with Grignard reagents by the cleavage of C-O(alkyl) bonds. Diverse transformations were achieved using simple, inexpensive chromium(II) precatalyst combining imino auxiliary at room temperature. It offers a new avenue for buildup functionalized aromatic aldehydes with high efficiency and selectivity.
Formation of a carbonyl group ortho to a biaryl structure or a 6H-dibenzopyran by a palladium/norbornene-catalyzed ordered reaction sequence
Della Ca, Nicola,Fontana, Marco,Xu, Di,Cremaschi, Mirko,Lucentini, Riccardo,Zhou, Zhi-Ming,Catellani, Marta,Motti, Elena
, p. 6389 - 6401 (2015/08/18)
Abstract Developments are reported in the catalytic synthesis of biaryls containing an ortho-carbaldehyde or 6H-dibenzopyrans in the presence of palladium/norbornene as catalyst. The reaction of o-substituted aryl iodides and o-bromobenzyl alcohols proceeds by unsymmetrical aryl-aryl coupling to form a seven-membered oxapalladacycle intermediate, which may undergo an intramolecular redox process to form carbonyl groups or a C-O coupling to six-membered cyclic ethers. The predominant formation of dibenzopyrans as well as of biaryl structures containing the oxidized CHO group in one ring and the reduced CH2OH in the other is described along with some mechanistic insights.
Catalytic oxidative cyclization of 2′-arylbenzaldehyde oxime ethers under photoinduced electron transfer conditions
Hofstra, Julie L.,Grassbaugh, Brittany R.,Tran, Quan M.,Armada, Nicholas R.,De Lijser, H. J. Peter
, p. 256 - 265 (2016/09/09)
A series of 2′-arylbenzaldehyde oxime ethers were synthesized and shown to generate the corresponding phenanthridines upon irradiation in the presence of 9,10-dicyanoanthracene in acetonitrile. Mechanistic studies suggest that the oxidative cyclization reaction sequence is initiated by an electron transfer step followed by nucleophilic attack of the aryl ring onto the nitrogen of the oxime ether. A concave downward Hammett plot is presumably the result of a change in charge distribution in the radical cation species with strongly electron-donating substituents that yields a less electrophilic nitrogen atom and a decreased amount of cyclized product. The reaction is selective (no nitrile byproduct is formed unlike other photochemical reactions involving aldoxime ethers) as well as regiospecific when using 2′-aryl groups with metasubstituents, making this reaction a useful alternative for preparing substituted phenanthridines.
A sequential Pd/norbornene-catalyzed process generates o- biaryl carbaldehydes or ketones via a redox reaction or 6 h -dibenzopyrans by C-O ring closure
Motti, Elena,Ca, Nicola Della,Xu, Di,Piersimoni, Anna,Bedogni, Elena,Zhou, Zhi-Ming,Catellani, Marta
supporting information, p. 5792 - 5795 (2013/01/15)
o-Biaryl carbaldeydes and ketones are obtained through the one-pot reaction of o-aryl iodides with o-bromobenzyl alcohols under the catalytic action of Pd and norbornene, in the presence of a base. The same reaction can also give dibenzopyrans by Pd and norbornene catalysis with a different termination, leading to C-O ring closure. In both cases the process first leads to a five-membered palladacycle, which controls C-C coupling, then to a seven-membered oxapalladacycle, which gives aldehydes and ketones or dibenzopyrans.
First and mild synthesis of fluorene-9-malonic acid and some substituted derivatives via the intramolecular hydroarylation of 2-phenylbenzylidenemalonic acids
Chosson, Elizabeth,Rochais, Christophe,Legay, Remi,Santos, Jana Sopkova De Oliveira,Rault, Sylvain,Dallemagne, Patrick
experimental part, p. 2548 - 2554 (2011/04/25)
Hitherto unknown fluorene-9-malonic acid and some substituted derivatives were easily synthesized in very mild conditions through the intramolecular hydroarylation of 2-phenylbenzylidenemalonic acids issued from the corresponding biphenylcarboxaldehydes.
