13683-85-7Relevant articles and documents
Facile preparation of pyrimidinediones and thioacrylamides: Via reductive functionalization of amides
Trillo, Paz,Slagbrand, Tove,Tinnis, Fredrik,Adolfsson, Hans
, p. 9159 - 9162 (2017)
The development of an efficient protocol for the reductive functionalization of amides into pyrimidinediones and amino-substituted thioacrylamides is presented. Enamines are generated in a highly chemoselective amide hydrosilylation reaction catalyzed by
SmI2(H2O)n Reduction of Electron Rich Enamines by Proton-Coupled Electron Transfer
Kolmar, Scott S.,Mayer, James M.
supporting information, p. 10687 - 10692 (2017/08/15)
Samarium diiodide in the presence of water and THF (SmI2(H2O)n) has in recent years become a versatile and useful reagent, mainly for reducing carbonyl-type substrates. This work reports the reduction of several enamines by SmI2(H2O)n. Mechanistic experiments implicate a concerted proton-coupled electron transfer (PCET) pathway, based on various pieces of evidence against initial outer-sphere electron transfer, proton transfer, or substrate coordination. A thermochemical analysis indicates that the C-H bond formed in the rate-determining step has a bond dissociation free energy (BDFE) of ～32 kcal mol-1. The O-H BDFE of the samarium aquo ion is estimated to be 26 kcal mol-1, which is among the weakest known X-H bonds of stable reagents. Thus, SmI2(H2O)n should be able to form very weak C-H bonds. The reduction of these highly electron rich substrates by SmI2(H2O)n shows that this reagent is a very strong hydrogen atom donor as well as an outer-sphere reductant.
Mechanistic Studies on the Catalytic Oxidative Amination of Alkenes by Rhodium(I) Complexes with Hemilabile Phosphines
Jimenez, M. Victoria,Bartolome, M. Isabel,Perez-Torrente, Jesus J.,Gomez, Daniel,Modrego, F. Javier,Oro, Luis A.
, p. 263 - 276 (2013/03/14)
Cationic rhodium(I) complexes with P,O-functionalised arylphosphine ligands are efficient catalysts for the regioselective anti-Markovnikov oxidative amination of styrene with piperidine. The mechanism of the catalytic reaction has been investigated by spectroscopic means under stoichiometric and catalytic conditions. In the presence of piperidine, the catalyst precursor [Rh{κ2-P,O-Ph2P(CH2)3OEt}2]+ (5) gave the piperidine complex [Rh{κ1-P-Ph2P(CH2)3OEt}2(HNC5H10)2]+ (8) that was transformed into the neutral amido-piperidine species [Rh{κ1-P-Ph2P(CH2)3OEt}2(NC5H10)(HNC5H10)] (9) under thermal conditions. NMR studies performed in the presence of styrene under catalytic conditions showed that 9 is a key species in the catalytic oxidative amination of styrene. Related cyclooctadiene-containing catalyst precursors [Rh(cod){κ1-P-Ph2P(CH2)3OEt}n]+ (n=1, 2) also gave 9 under the same conditions. The proposed catalytic cycle has been established by a series of DFT calculations including the transition states of the key steps that have been identified and characterised. These studies have shown that, after elimination of the enamine, regeneration of catalytic active species takes place by direct transfer of the proton of a piperidine ligand to the alkyl group resulting from the insertion of styrene into the Rh-H bond and formation of ethylbenzene. Against the expectations, the formation of a dihydride intermediate by NH oxidative addition is a highly energy-demanding process. Catalyst 5 has also been applied for the oxidative amination of substituted vinylarenes with several secondary cyclic and acyclic amines.
