modern organic synthesis, chemoselectivity is recognized as an important factor in the development of new methodologies. Chemoselective nucleophilic addition to amide carbonyl centers is a challenge because classical methods require harsh reaction conditions to overcome the poor electrophilicity of the amide carbonyl group. We have successfully developed a reductive nucleophilic addition of mild nucleophiles
Flexible and Chemoselective Oxidation of Amides to α-Keto Amides and α-Hydroxy Amides
作者:Aurélien de la Torre、Daniel Kaiser、Nuno Maulide
DOI:10.1021/jacs.7b02983
日期:2017.5.17
A suite of flexible and chemoselective methods for the transition-metal-free oxidation of amides to α-keto amides and α-hydroxy amides is presented. These highly valuable motifs are accessed in good to excellent yields and stereoselectivities with high functional group tolerance. The utility of the method is showcased by the formal synthesis of a potent histone deacetylase inhibitor.
Practical Access to Amines by Platinum-Catalyzed Reduction of Carboxamides with Hydrosilanes: Synergy of Dual Si−H Groups Leads to High Efficiency and Selectivity
The synergetic effect of two Si-H groups leads to efficient reduction of carboxamides to amines by platinum catalysts under mild conditions The rate of the reaction is dependent on the distance of two Si-H groups, 1,1,3,3-tetramethyidisiloxane (TMDS) and 1,2-bis(dimethylsilyl)benzene are found to be an effective reducing reagent. The reduction of amides having other reducible functional groups such as NO2, CO2R, CN, C=C, Cl, and Br moieties proceeds with these groups remaining intact, providing a reliable method for the access to functionalized amine derivatives. The platinum-catalyzed reduction of amides with polymethylhydrosiloxane (PMHS) also proceeds under mild conditions. The reaction is accompanied by automatic removal of both platinum and silicon wastes as insoluble silicone resin, and the product is obtained by simple extraction. A mechanism involving double oxidative addition of TMDS to a platinum center is discussed.
Dual Si–H effects in platinum-catalyzed silane reduction of carboxamides leading to a practical synthetic process of tertiary-amines involving self-encapsulation of the catalyst species into the insoluble silicone resin formed
Combination of commercially available platinum catalysts with siloxanes containing more than two Si-H groups is found to be an efficient catalyst system for the reduction of carboxamides to amines. In particular, facile removal of silicon and platinum residues from the product can be achieved by the use of polymethylhydrosiloxanes as reducing reagents. (c) 2006 Elsevier Ltd. All rights reserved.