Fast transimination in organic solvents in the absence of proton and metal catalysts. A key to imine metathesis catalyzed by primary amines under mild conditions

Abstract

Amine-imine exchange reactions of sterically unhindered reactants were found to be surprisingly fast at room temperature in a variety of nonaqueous solvents in the absence of proton and metal catalysts. The reaction mechanism suggested by ab initio calculations in the gas phase involves nucleophilic addition to the CN bond in concert with proton transfer from the amine NH bond to the imine nitrogen via a highly imbalanced transition state. These very fast transimination reactions were utilized in the catalysis of imine metathesis. Imine metathesis, usually carried out in organic solvents at high temperature in the presence of metal catalysts, occurs smoothly at room temperature in the presence of primary amines under nonacidic conditions as a result of coupled transimination processes. Kinetic data fully consistent with the proposed reaction mechanism were obtained. © 2013 The Royal Society of Chemistry

Vitrimers: permanent organic networks with glass-like fluidity

“…10a), also associative pathways in absence of water via either amine exchange 61 (Fig. 10b) or imine metathesis (Fig.…”

Non‐Heme Imine‐Based Iron Complexes as Catalysts for Oxidative Processes

“…[48,49] Furthermore,ametal cation such as Fe(II) or Fe(III) can act as atemplate for imine bond formation with the consequent in-situ generation of the complex. [85] Despite this significant advantage,i mines are far less investigated ligands than amines in iron oxidation catalysis.…”

“…[44][45][46][47] Thed evelopment of non-hemea mine-based iron catalysts has been accompanied over the years by ap arallels tudy of non-heme imine-based ironc ounterparts,a lthough the latter received less interest probably due to the conviction that imines (or Schiff bases) are not robust enough to be conveniently employed in typical oxidation conditions.Y et, some imine-based complexes proved to be stable enough to serve as oxidation catalysts (vide infra). Moreover, imine ligands are even easier to synthesize than the corresponding amines [48][49][50] and this represents asignificant advantage in catalyst design and preparation. Thea im of this review article is to describe the state of art in non-heme imine-based iron catalysts for C À H, C=Ca nd So xidation.…”

Reactivity of carbonyl and phosphoryl groups at calixarenes

“…In this overview, focussing on processes controlled by multifunctional biological substrates. Interesting chiral calixarenes and involving carbonyl and phosphoryl discrimination with a 39% diastereomeric excess was groups, we have shown examples of high levels of observed (45) in the reversible imine formation (47) with cooperation among recognition and catalytic sites equimolar (5.0 mM) L-serine ethyl ester hydrochloride conveniently preorganised on a calixarene platform. in the presence of excess solid K 2 CO 3 (acetonitrile, Special reactivity features induced by proximity of 258C).…”