7469-24-1Relevant articles and documents
Highly Active Platinum Catalysts for Nitrile and Cyanohydrin Hydration: Catalyst Design and Ligand Screening via High-Throughput Techniques
Xing, Xiangyou,Xu, Chen,Chen, Bo,Li, Chengcheng,Virgil, Scott C.,Grubbs, Robert H.
supporting information, p. 17782 - 17789 (2019/01/04)
Nitrile hydration provides access to amides that are indispensable to researchers in chemical and pharmaceutical industries. Prohibiting the use of this venerable reaction, however, are (1) the dearth of biphasic catalysts that can effectively hydrate nitriles at ambient temperatures with high turnover numbers and (2) the unsolved challenge of hydrating cyanohydrins. Herein, we report the design of new "donor-acceptor"-type platinum catalysts by precisely arranging electron-rich and electron-deficient ligands trans to one other, thereby enhancing both the nucleophilicity of the hydroxyl group and the electrophilicity of the nitrile group. Leveraging a high-throughput, automated workflow and evaluating a library of bidentate ligands, we have discovered that commercially available, inexpensive DPPF [1,1′-ferrocenendiyl-bis(diphenylphosphine)] provides superior reactivity. The corresponding "donor-acceptor"-type catalyst 2a is readily prepared from (DPPF)PtCl2, PMe2OH, and AgOTf. The enhanced activity of 2a permits the hydration of a wide range of nitriles and cyanohydrins to proceed at 40 °C with excellent turnover numbers. Rational reevaluation of the ligand structure has led to the discovery of modified catalyst 2c, harboring the more electron-rich 1,1′-bis[bis(5-methyl-2-furanyl)phosphino] ferrocene ligand, which demonstrates the highest activity toward hydration of nitriles and cyanohydrins at room temperature. Finally, the correlation between the electron-donating ability of the phosphine ligands with catalyst efficiencies of 2a, 2c, 2d, and 2e in the hydration of nitrile 7 are examined, and the results support the "donor-acceptor" hypothesis.
Heterocycles as Masked Diamide/Dipeptide Equivalents. Formation and Reactions of Substituted 5-(Acylamino)oxazoles as Intermediates en route to the Cyclopeptide Alkaloids
Lipshutz, Bruce H.,Hungate, Randall W.,NcCarthy, Keith E.
, p. 7703 - 7713 (2007/10/02)
A variety of novel 2,4-dialkyl-5-(acylamino)oxazoles have been prepared by using either amide nitriles or diamides/dipeptides as starting materials.Ring closure calls for the use of trifluoroacetic acid/trifluoroacetic acid anhydride or an acid halide in
