Nucleophilic radical addition

Y, this bond is at first going to be a two-center, three-electron bond (H5C6.. Y). This process of nucleophile addition can and must be viewed as an inner-sphere electron transfer. In other words, formation of the new bond is connected with a transfer of the electron to phenyl radical. Therefore, the good electron donor character of Y is necessary for this step eventually to lead to the efficient formation of (H5C6Y), i.e., the product anion radical. Galli and Gentili (1998) have evaluated the thermodynamic driving force (TDDF) of the nucleophile/radical addition step. With respect to this step, they classified a nucleophile... 

Selective Oxido-Reductive Processes by Nucleophilic Radical Addition under Mild Conditions... 

In 1990, Porta and co-workers [6] reported the first nucleophilic radical addition to aldimines promoted by aqueous TiCl3, based on a one-pot tricomponent reaction involving an aromatic amine, a generic aldehyde, and an arene-diazonium salt (Equation 14.15). 

Scheme 14.7 General mechanism for the nucleophilic radical addition to imines mediated by Ti (IV).

Nucleophilic Radical Addition Promoted by TiCl3/Pyridine Systems... 

The classical Mannich aminomethylation is one of the most important ionic carbon-carbon bond forming reactions in organic chemistry [35]. However, only substituents with electron-withdrawing groups are suitable for the ionic addition. Electron-donating groups directly bonded to the carbon-centered radical favor nucleophilic radical addition to methylene-iminium salts. Thus, the radical-type Mannich reaction provides products which are complementary to those obtained with the classical ionic reaction. 

In one of these contributions, organic synthetic procedures regarding nucleophilic radical addition under mild conditions is described, underlining and confirming the idea that high reactivity is not necessarily associated with low selectivity. 

In this example, a relatively strong chiral Lewis acid 5 is employed in order to activate the a,yS-unsaturated ester 4 and promote nucleophilic radical additions to the f position. It is noted that the Lewis acid presumably coordinates the oxygen lone pair on the carbonyl from the side opposite the ring oxygen [6], and thus chirality is imparted by the atropisomeric BINOL ligand. Low levels of asymmetric induction were observed. 

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