Organic electrochemistry and radical/radical ion chemistry / Électrochimie organique et chimie des radicaux/radicaux ions

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The main objective of my research is to identify factors which influence the reactivity of reactive intermediates (radicals, radical ions, and chemisorbed hydrogen (Hads)), and to comprehend at the molecular level, how these factors affect their reactivity. I. REACTIVITY of amidyl radicals.- We will synthesize new model precursors of cyclic amidyls constrained to react in the pi electronic state (unpaired e- in a pi orbital) and precursors allowing to compare the reactivity of the pi and sigma (unpaired e- in the plane of the sigma bonds) states. II. RING CONTRACTION of N-substituted lactams.- We discovered that photolysis of N-chloro- and N-Omesyl-lactams (6- and 7-membered ring) gives the corresponding ring-contracted nitrogen heterocycle with 100% retention of configuration at the migrating carbon. The proposed research will involve: mechanistic studies (influence of substituents at various positions of the lactam ring, of the conformational bias of the ring, and of isotopic labelling); development of general syntheses of N-hydroxylactams; synthesis and diazotation of N-aminolactams; applications to the synthesis of N-heterocyclic natural products. III. ELECTROORGANIC CHEMISTRY.- 3a. Cleavage of nitro radical anions.- We will generate, by electroreduction, the radical anion of a series of 1-nitrocyclopropanes / cyclobutanes and 1-(4-nitrophenyl)-cyclopropanes / cyclobutanes having various substituents at positions 1 and 2 (alkyl groups, electron-donating /-attracting groups) and determine the type of cleavage (homolytic vs. heterolytic) and their rate of cleavage using cyclic voltammetry (homogeneous redox catalysis for very rapid cleavage), coulometry and preparative electrolysis (product identification). 3b. ElectroCatalytic Hydrogenation (ECH).- ECH of an organic compound involves reaction of Hads (generated on the electrode surface by reduction of water) with the adsorbed org. substrate. Surface and kinetic studies on single crystals aims at i) identifying / understanding the factors influencing the efficiency and selectivity, ii) identifying the nature of H(ads) active in hydrogenation, and iii) determining how the electrocatalyst and reaction conditions affect the rates (hydrogenation vs. H desorption).