23132-29-8Relevant articles and documents
Hydration of Aliphatic Nitriles Catalyzed by an Osmium Polyhydride: Evidence for an Alternative Mechanism
Babón, Juan C.,Esteruelas, Miguel A.,López, Ana M.,O?ate, Enrique
, p. 7284 - 7296 (2021/05/29)
The hexahydride OsH6(PiPr3)2 competently catalyzes the hydration of aliphatic nitriles to amides. The main metal species under the catalytic conditions are the trihydride osmium(IV) amidate derivatives OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2, which have been isolated and fully characterized for R = iPr and tBu. The rate of hydration is proportional to the concentrations of the catalyst precursor, nitrile, and water. When these experimental findings and density functional theory calculations are combined, the mechanism of catalysis has been established. Complexes OsH3{κ2-N,O-[HNC(O)R]}(PiPr3)2 dissociate the carbonyl group of the chelate to afford κ1-N-amidate derivatives, which coordinate the nitrile. The subsequent attack of an external water molecule to both the C(sp) atom of the nitrile and the N atom of the amidate affords the amide and regenerates the κ1-N-amidate catalysts. The attack is concerted and takes place through a cyclic six-membered transition state, which involves Cnitrile···O-H···Namidate interactions. Before the attack, the free carbonyl group of the κ1-N-amidate ligand fixes the water molecule in the vicinity of the C(sp) atom of the nitrile.
Enantioselective Ruthenium(II)/Xyl-SunPhos/Daipen-Catalyzed hydrogenation of γ-Ketoamides
Zhao, Mengmeng,Li, Wanfang,Li, Xiaoming,Ren, Kai,Tao, Xiaoming,Xie, Xiaomin,Ayad, Tahar,Ratovelomanana-Vidal, Virginie,Zhang, Zhaowuo
, p. 6164 - 6171 (2014/07/21)
A0series of γ-hydroxy amides were synthesized with high ena~tioselectivities (up to 99%) usyng asymmetric hydrogenation of the corresponding γ-ketoamides in the presence of Ru-Xyl-SunPhos-Daipen catalyst providing key building blocks for a variety of natu
Chemical and microsomal oxidation of tertiary amides: Regio- and stereoselective aspects
Iley, Jim,Tolando, Roberto,Constantino, Luis
, p. 1299 - 1305 (2007/10/03)
The conformationally restricted tertiary amides N-methyl-2-pyrrolidone 6, N-methyl-2-piperidone 7 and N-methyl-ε-caprolactam 8 were oxidised by 5,10,15,20-tetraphenylporphyrinatoiron(III) chloride/tert-butyl hydroperoxide (TPPFe/ButOOH) and by phenobarbital-induced rat liver microsomes. The products were the N-demethylated lactams together with the analogous N-methylimides and norimides. For the TPPFe/ButOOH reaction ring oxidation is preferred to N-demethylation, paralleling the relative stabilities of the corresponding intermediate carbon-centred radicals as calculated by the AM1 semi-empirical method. In contrast, the microsomal reaction of the N-methyllactams strongly favours N-demethylation, demonstrating that hydrogen atom abstraction from the alkyl group Z to the amide carbonyl oxygen atom is preferred. The chiral tertiary amides N-methyl-N-(1-phenylethyl)benzamide 9 and N-methyl-5-phenyl-2-pyrrolidone 10 were also oxidised by TPPFe/ButOOH and by phenobarbital-induced rat liver microsomes. Using TPPFe/ButOOH, loss of the secondary alkyl group of 9 is preferred by a factor of ca. 6. Similarly, ring oxidation of 10 is favoured over demethylation by a factor of 9. For the microsomal reaction of (R)-9 dealkylation is preferred over demethylation by a factor of 1.7, whereas for (S)-9 demethylation is favoured by a factor of 1.25. For the microsomal reaction of (R)-10 and (S)-10 ring oxidation at the 5-position of the pyrrolidone ring is preferred over demethylation by factors of ca. 4 and 9 for the two isomers, respectively, and the (S)-enantiomer undergoes ring oxidation 2-3 times more readily than the (R)-enantiomer. For both 9 and 10 there is negligible stereochemical influence of the chiral centre upon the N-demethylation reaction. The results show that the stereochemical preference of the microsomal N-dealkylation reaction is modest.
