1380395-17-4Relevant articles and documents
Stereoselective Synthesis of Methylene Oxindoles via Palladium(II)-Catalyzed Intramolecular Cross-Coupling of Carbamoyl Chlorides
Le, Christine M.,Sperger, Theresa,Fu, Rui,Hou, Xiao,Lim, Yong Hwan,Schoenebeck, Franziska,Lautens, Mark
supporting information, p. 14441 - 14448 (2016/11/13)
We report a highly robust, general and stereoselective method for the synthesis of 3-(chloromethylene)oxindoles from alkyne-tethered carbamoyl chlorides using PdCl2(PhCN)2 as the catalyst. The transformation involves a stereo- and regioselective chloropalladation of an internal alkyne to generate a nucleophilic vinyl PdII species, which then undergoes an intramolecular cross-coupling with a carbamoyl chloride. The reaction proceeds under mild conditions, is insensitive to the presence of moisture and air, and is readily scalable. The products obtained from this reaction are formed with >95:5 Z:E selectivity in nearly all cases and can be used to access biologically relevant oxindole cores. Through combined experimental and computational studies, we provide insight into stereo- and regioselectivity of the chloropalladation step, as well as the mechanism for the C-C bond forming process. Calculations provide support for a mechanism involving oxidative addition into the carbamoyl chloride bond to generate a high valent PdIV species, which then undergoes facile C-C reductive elimination to form the final product. Overall, the transformation constitutes a formal PdII-catalyzed intramolecular alkyne chlorocarbamoylation reaction.
A general synthesis of indole-3-carboxylic esters by palladium-catalyzed direct oxidative carbonylation of 2-alkynylaniline derivatives
Gabriele, Bartolo,Veltri, Lucia,Mancuso, Raffaella,Salerno, Giuseppe,Costa, Mirco
, p. 2549 - 2559 (2013/08/23)
A general synthesis of indole-3-carboxylic esters by direct Pd-catalyzed oxidative carbonylation of readily available 2-alkynylaniline derivatives is reported. In particular, 2-alkynylanilines bearing an internal triple bond and a secondary amino group (1) were directly converted into indole-3-carboxylic esters 2 in fair to good yields (50-84%) when let to react with CO, O 2, and an alcohol in the presence of the PdI2/ KI catalytic system, under relatively mild conditions [100 °C and 20 atm (at 25 °C) of a 4:1 mixture CO/air]. On the other hand, under similar conditions, but in the presence of HC(OMe)3, 2-alkynylanilines bearing an internal triple bond and a primary amino group (7) afforded 1-(dimethoxymethyl) indole-3-carboxylic esters 9 through the intermediate formation of N-(dimethoxymethyl)-2-alkynylaniline derivatives II. Compounds 9 could be conveniently converted into Nunsubstituted indole-3-carboxylic esters 10 by a simple acidic treatment carried out in MeOH/H2O at 80 °C.
