77656-96-3Relevant academic research and scientific papers
Enabling CO Insertion into o-Nitrostyrenes beyond Reduction for Selective Access to Indolin-2-one and Dihydroquinolin-2-one Derivatives
Yang, Li,Shi, Lijun,Xing, Qi,Huang, Kuo-Wei,Xia, Chungu,Li, Fuwei
, p. 10340 - 10348 (2018/10/20)
The transition metal-catalyzed reductive cyclization of o-nitrostyrene in the presence of carbon monoxide (CO) has been developed to be a general synthetic route to an indole skeleton, wherein CO was used as a reductant to deoxidize nitroarene into nitrosoarene and/or nitrene with CO2 release, but the selective insertion of CO into the heterocyclic product with higher atom economy has not yet been realized. Herein, the Pd-catalyzed reduction of o-nitrostyrene by CO and its regioselective insertion were efficiently achieved to produce synthetically useful five- and six-membered benzo-fused lactams. Detailed investigations revealed that the chemoselectivity to indole or lactam was sensitive to the nature of the counteranions of Pd2+ precursors, whereas ligands significantly decided the carbonylative regioselectivity by different reaction pathways. Using PdCl2/PPh3/B(OH)3 (condition A), an olefin hydrocarboxylation was primarily initiated followed by partial reduction of the NO2 moiety and cyclization reaction to give N-hydroxyl indolin-2-one, which was further catalytically reduced by CO to afford the indolin-2-one as the final product with up to 95% yield. When the reaction was conducted under the Pd(TFA)2/BINAP/TsOH·H2O system (condition B), complete deoxygenation and carbonylation of the NO2 group occurred initially to yield the corresponding isocyanate followed by internal hydrocyclization to generate 3,4-dihydroquinolin-2-one with up to 98% yield. Importantly, the methodology could be efficiently applied in the synthesis of marketed drug Aripiprazole.
Palladium-catalyzed decarboxylative coupling of potassium nitrophenyl acetates with aryl halides
Shang, Rui,Huang, Zheng,Chu, Ling,Fu, Yao,Liu, Lei
supporting information; experimental part, p. 4240 - 4243 (2011/10/09)
A palladium-catalyzed decarboxylative cross-coupling of potassium 2- and 4-nitrophenyl acetates with aryl chlorides and bromides has been developed. Because the nitro group can be readily converted to many other functional groups, the new reaction provides a useful method for the preparation of diverse 1,1-diaryl methanes and their derivatives.
Experiments on the Chaperon effect in the nitration of aromatics
Strazzolini, Paolo,Giumanini, Angelo G.,Runcio, Antonio,Scuccato, Massimo
, p. 952 - 958 (2007/10/03)
A nitro group may be effectively delivered to the ortho position of alkylbenzenes, provided that a suitable chaperon function is located in α- position and a dilute of HNO3 in CH2Cl2 is used. The carbonyl function of an aldehyde or ketone is the best choice, but a carboxyl, alkoxycarbonyl, and amide groups all work well. The ether function showed a less pronounced ortho orientation effect, whereas the hydroxyl group was too prone to oxidation. Side reactions were minimal under the conditions employed. A para chaperon effect was seemingly at work in the CH2Cl2 nitration of benzenepropanenitrile. All the results were compared with the corresponding classical nitration in H2SO4.
α-Nitroarylation of Ketones and Esters: An Exceptionally Facile Synthesis of Indoles, 2-Indolinones, and Arylacetic Acids
RajanBabu, T. V.,Chenard, Bertrand L.,Petti, Michael A.
, p. 1704 - 1712 (2007/10/02)
Silyl enol ethers and ketene silyl acetals add to aromatic nitro compounds in the presence of fluoride ion sources to give dihydroaromatic nitronates which are readily oxidized to α-nitroaryl carbonyl compounds by DDQ or Br2.These versatile intermediates are readily converted into indoles or 2-indolinones by reductive cyclization.Since halogen substituents on the aromatic ring are not displaced in the initial alkylation reaction, nucleophilic substitution of these groups, followed by functional group manipulations of the nitro group, permits easy access to indoles, 2-indolinones, and arylacetic acids with varied substitution patterns.
