Time-Resolved Infrared Study on the Photochemistry of O-Fluoroformyl- and O-Chlorooxalyl-9-fluorenone Oxime:  The Reactivity of the Fluoroformyl Radical in Acetonitrile Solution

Abstract

This note describes the photochemistry of O-chlorooxalyl- and O-fluoroformyl-9-fluorenone oxime. The solution photochemistry of both precursors was investigated by time-resolved step/scan FTIR spectroscopy. Experiments on O-chlorooxalyl-9-fluorenone oxime only allowed for detection of CO2 and bleaching of the precursor, indicating predominant N-O cleavage. The chlorocarbonyl radical, ClCO*, was not detected. In contrast, TRIR investigations on fluoroformyl oxime 2 gave evidence for formation of the fluoroformyl radical FCO* (3), which rapidly adds to the solvent acetonitrile, yielding a fluoroformyl-functionalized iminyl radical 4. Its reaction with triplet molecular oxygen, on the other hand, is impeded by an activation enthalpy that has been calculated as deltaH# = 3.2 kcal/mol.

Iminyl Radicals from α-Azido o-Iodoanilides via 1,5-H Transfer Reactions of Aryl Radicals: New Transformation of α-Azido Acids to Decarboxylated Nitriles

“…Thus, the general chemical evidence furnished by the above findings strictly suggests that anilides 1 , except when an aryl was present on the α-carbon, were able to cleanly afford the respective α-(aminocarbonyl)iminyl radicals 4 via very fast 1,5-hydrogen transfer of primary aryl radicals 2 followed by rapid extrusion of dinitrogen from the resultant azidoalkyl radicals 3 (Scheme ). This fact was further substantiated by our general failure to observe any deiodinated substrate, which might have resulted from tin hydride reduction of aryl radical 2 and/or translocated azidoalkyl radical 3 .…”

Photochemical Grafting and Patterning of Metallic Surfaces by Organic Layers Derived from Acetonitrile

“…The attack of the radical takes place on the carbon atom of the nitrile group. This reaction has already been reported in the literature: 76 (i) the cyanobutyl radical cyclizes to give cyclopentanone through an intermediate iminyl radical, 77 (reaction rate: 4.5 Â 10 2 s À1 at 259 K); 78 (ii) iminyl radicals are generated by 5-exo cyclization of alkyl, vinyl, and aryl C-centered radicals with nitriles; 79 (iii) the fluoroformyl radical reacts with acetonitrile to give an iminyl radical 80 and the ESR spectrum of iminyl radicals has been observed. 81 In Scheme 4, the iminyl radical can be hydrogenated to an imine by hydrogen atom transfer from ACN, regenerating a cyanomethyl radical [R5]; therefore, the reaction is a chain reaction.…”

Recent Advances in the Synthesis and Transformation of Carbamoyl Fluorides, Fluoroformates, and Their Analogues

“…In addition to O=CF 2 , carbonyl chloride fluoride (O=CFCl) can react with alcohols or oximes to produce fluoroformates [65,66] . 1‐(1‐Adamanty1)‐1‐methyl‐ethoxycarbonyl (Adpoc) fluoride ( 207 ) is a reactive agent, allowing the introduction of Adpoc group into amino acids under mild conditions with high yields [65] .…”