14990-66-0Relevant articles and documents
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.
1,3-Dipolar cycloaddition reactivities of perfluorinated aryl azides with enamines and strained dipolarophiles
Xie, Sheng,Lopez, Steven A.,Ramstr?m, Olof,Yan, Mingdi,Houk
supporting information, p. 2958 - 2966 (2015/03/18)
The reactivities of enamines and predistorted (strained) dipolarophiles toward perfluoroaryl azides (PFAAs) were explored experimentally and computationally. Kinetic analyses indicate that PFAAs undergo (3 + 2) cycloadditions with enamines up to 4 orders of magnitude faster than phenyl azide reacts with these dipolarophiles. DFT calculations were used to identify the origin of this rate acceleration. Orbital interactions between the cycloaddends are larger due to the relatively low-lying LUMO of PFAAs. The triazolines resulting from PFAA-enamine cycloadditions rearrange to amidines at room temperature, while (3 + 2) cycloadditions of enamines and phenyl azide yield stable, isolable triazolines. The 1,3-dipolar cycloadditions of norbornene and DIBAC also show increased reactivity toward PFAAs over phenyl azide but are slower than enamine-azide cycloadditions.
New nucleophilic rearrangement in the mechanism of the three-component domino cyclisation affording fluoroalkylated (pyrrolo)quinazolines
Paleta, Old?ich,Dolensky, Bohumil,Pale?ek, Ji?í,Kví?ala, Jaroslav
supporting information, p. 1 - 11 (2014/01/06)
The following mechanism steps were verified for the three-component domino cyclisation affording (pyrrolo)quinazolines from 2-(aminomethyl)aniline, a very reactive oxo compound and "usual" oxo compound. The first step was a rapid reaction of very reactive oxo compound (trifluoropyruvate or hexafluoroacetone) with benzylic amino group to form hemiaminal, but not imine; the second step was the reaction of oxo compound with aromatic amino group to form imine (Schiff base) being in equilibrium with its enamine form; the third step was an intramolecular attack of the hemiaminal carbon by the enamine carbon followed by a new nucleophilic rearrangement to form tetrahydropyrimidine cycle; the forth step was closure of the lactam ring, if ester group was available as in trifluoropyruvate.2013 Elsevier B.V. All rights reserved.
