10433-34-8Relevant academic research and scientific papers
Free radical-mediated aryl amination and its use in a convergent [3 + 2] strategy for enantioselective indoline α-amino acid synthesis
Viswanathan, Rajesh,Prabhakaran, Erode N.,Plotkin, Michael A.,Johnston, Jeffrey N.
, p. 163 - 168 (2007/10/03)
The scope of aryl radical additions to the nitrogen of azomethines is described. Aryl, trifluoromethyl alkyl, and α,β-unsaturated ketimines engage in regioselective aryl-nitrogen bond formation via 5-exo cyclizations of an aryl radical to azomethine nitrogen. Selectivity for carbon-nitrogen over carbon-carbon bond formation is generally high (>95:5) and competes only with direct aryl radical reduction by stannane (0-10%). α-Ketoimines are a promising new class of carbon radical acceptors for which no competitive aryl radical reduction is observed. The reaction conditions are pH-neutral and are therefore among the mildest methods available for amination of an aromatic ring. The ketimines examined did not suffer from competitive reduction by stannane, offering an advantage over the use of diazo and azide functional groups as nitrogen sources for carbon radicals. The free radical-mediated aryl amination was sequenced with the O'Donnell phase transfer-catalyzed enantioselective alkylation strategy of glycinyl imine to provide either enantiomer of indoline α-amino acids with high ee. These new constrained phenyl alanine derivatives are now readily available for evaluation across a variety of applications.
Nonconventional carbon additions to azomethines. Aryl amination/idoline synthesis by direct aryl radical addition to azomethine nitrogen
Johnston, Jeffrey N.,Plotkin, Michael A.,Viswanathan, Rajesh,Prabhakaran, Erode N.
, p. 1009 - 1011 (2007/10/03)
(matrix presented) The generality of a new method for aryl amination has been defined. Ketimines derived from o-bromophenethylamine cyclize to the N-substituted indoline when treated with nBu3SnH and a radical initiator. The pH-neutral conditions tolerate base- and acid-sensitive functionality. The observed regioselectivity is nonconventional for addition reactions involving carbon radicals and carbon-heteroatom π-bonds.
Stereochemical Study of Imines and their N-Borane Adducts by 1H, 11B, 13C and 15N NMR
Ariza-Castolo, Armando,Paz-Sandoval, M. Angeles,Contreras, Rosalinda
, p. 520 - 526 (2007/10/02)
The synthesis and NMR spectra of the N-borane adducts of two diimines, N-borane-bis(α-phenylethylidene)ethylenediamine and N-borane-bis(α-phenylbenzylidene)ethylenediamine, and four imines, N-borane-α-methylethylidene-2-phenylethylamine, two N-borane-α-ph
Photolysis of Alkyl Azides. Evidence for a Nonnitrene Mechanism
Kyba, Evan P.,Abramovitch, Rudolph A.
, p. 735 - 740 (2007/10/02)
The photolyses of nine sec- and tert-alkyl azides have been studied in detail.The products consist of imines derived from 1,2-shifts of groups on the alkyl carbon atom α to the azide nitrogen atom.No evidence of typical nitrene processes (aromatic substitution, aliphatic C-H insertion) was found.The imine product distributions are rationalized on the basis of a preferred migration orientation in the photochemically excited azide, along with a consideration of either ground or excited state rotational equilibration of the azide.Photolyses of selected azides carried out over an approximately 200 deg C temperature range allow an estimation of apparent activation energy differences between different group migrations.These energy differences are in the range of 70-493 cal/mol and are related to rotational equilibration of the alkyl azide.
