Free-Radical Chemistry of Imines

1995 ◽  
Vol 48 (2) ◽  
pp. 291 ◽  
Author(s):  
MJ Tomaszewski ◽  
J Warkentin ◽  
NH Werstiuk
Keyword(s):  
Free Radical ◽  
Rate Constants ◽  
Functional Group ◽  
Imino Group ◽  
Radical Chemistry ◽  
Chiral Induction ◽  
Aryl Radicals ◽  
Free Radical Chemistry ◽  
Cyclization Rate ◽  
Ortho Substituent

Aryl radicals bearing an aldimino functional group as part of an ortho substituent cyclized by addition to C and/or N of the imino group. When the choice was between 5-exo closure to C and 6-endo closure to N, the former predominated. However, 6-endo closure to C predominated over 5-exo cyclization to N in isomeric imines. Absolute values of cyclization rate constants were determined and an explanation for the unusual 6-endo preference is offered. Chiral induction in 6-endo cyclization to C of an aldimine from D-glyceraldehyde acetonide was observed, and its sense was determined.

Facile 5-endo ring closures to the azo group. A free radical synthesis of indazoles

1990 ◽  
Vol 68 (4) ◽  
pp. 575-580 ◽  
Author(s):  
Cheryl P. A. Kunka ◽  
John Warkentin
Keyword(s):  
Free Radical ◽  
Rate Constants ◽  
Functional Group ◽  
Radical Cyclization ◽  
Double Bonds ◽  
Aryl Radicals ◽  
Azo Group ◽  
Group A ◽  
Radical Clock

Five 1-alkyl-3-methylindazoles were prepared by treatment of 1-(2-bromophenyl)-1-methoxy-1-(2-alkylazo)ethanes with tri-n-butyl stannane and AIBN at 80 °C in benzene. Yields in the radical cyclization step ranged from 39 to 92%. 1-Phenyl-3-methylindazole was prepared by an analogous route but in very poor yield (<5%). Rate constants for the 5-endo radical closures [Formula: see text], estimated by the radical clock method, were 5.2 × 109 s−1 and 9.2 × 108 s−1 for two of the alkyl systems. Rate constants for analogous 5-endo cyclizations of aryl radicals onto C—C double bonds are much smaller than those for cyclizations to the azo functional group. Keywords: cyclization, radical; azo group, radical closure to; indazoles, radical synthesis of.

Free Radical Chemistry of Disinfection Byproducts. 2. Rate Constants and Degradation Mechanisms of Trichloronitromethane (Chloropicrin)

2007 ◽  
Vol 41 (3) ◽  
pp. 863-869 ◽  
Author(s):  
S. Kirkham Cole ◽  
William J. Cooper ◽  
Robert V. Fox ◽  
Piero R. Gardinali ◽  
Stephen P. Mezyk ◽  
...  
Keyword(s):  
Free Radical ◽  
Rate Constants ◽  
Disinfection Byproducts ◽  
Degradation Mechanisms ◽  
Radical Chemistry ◽  
Free Radical Chemistry

scholarly journals Free Radical Chemistry Enabled by Visible Light-Induced Electron Transfer

2016 ◽  
Vol 49 (10) ◽  
pp. 2295-2306 ◽  
Author(s):  
Daryl Staveness ◽  
Irene Bosque ◽  
Corey R. J. Stephenson
Keyword(s):  
Electron Transfer ◽  
Free Radical ◽  
Visible Light ◽  
Radical Chemistry ◽  
Free Radical Chemistry
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