Addition of tetrachloromethane to alkenes catalyzed by cobalt(II)-amine complex

The Persistent Radical Effect in Organic Synthesis

Radical-radical couplings are mostly nearly diffusion-controlled processes. Therefore, the selective cross-coupling of two different radicals is challenging and not a synthetically valuable transformation. However, if the radicals have different lifetimes and if they are generated at equal rates, cross-coupling will become the dominant process. This high cross-selectivity is based on a kinetic phenomenon called the persistent radical effect (PRE). In this Review, an explanation of the PRE supported by simulations of simple model systems is provided. Radical stabilities are discussed within the context of their lifetimes, and various examples of PRE-mediated radical-radical couplings in synthesis are summarized. It is shown that the PRE is not restricted to the coupling of a persistent with a transient radical. If one coupling partner is longer-lived than the other transient radical, the PRE operates and high cross-selectivity is achieved. This important point expands the scope of PRE-mediated radical chemistry. The Review is divided into two parts, namely 1) the coupling of persistent or longer-lived organic radicals and 2) "radical-metal crossover reactions"; here, metal-centered radical species and more generally longer-lived transition-metal complexes that are able to react with radicals are discussed-a field that has flourished recently.

Dual function of carbon tetrachloride: synthesis of chlorinated heterocycles

An efficient tandem approach to invent highly chlorinated and structurally diversified dihydropyridine fused heterocycles from easily accessible ortho-alkynylaldehydes and primary amines under metal-free conditions via four sequential bond formations is described. The proposed tandem route proceeds via a carbon tetrachloride-mediated 6-endo-dig ring closure followed by nucleophilic attack of the trichloromethyl anion.

Carbon Tetrachloride-Mediated Cyclization of (2-Alkynyl)arylaldimines for the Synthesis of Polychlorinated Nitrogen Heterocycles

An unprecedented use of carbon tetrachloride to mediate the 6-endo-dig cyclization of (2-alkynyl)arylaldimines, generated in situ from (2-alkynyl)arylaldehydes and primary amines, has been developed via formal insertion of C═N and C≡C bonds into a C-Cl bond under catalyst-free conditions, providing convenient access to a range of structurally diverse polychlorinated 1,2-dihydroisoquinolines and heteroarene-fused nitrogen heterocycles.

Radicals in transition metal catalyzed reactions? transition metal catalyzed radical reactions? - a fruitful interplay anyway: part 2. Radical catalysis by group 8 and 9 elements

This review summarizes the current status of transition metal catalyzed reactions involving radical intermediates in organic chemistry. This part focuses on radical-based methods catalyzed by group 8 and group 9 metal complexes. Reductive and redox-neutral coupling methods catalyzed by low-valent metal complexes as well as catalytic oxidative C-C bond formations are reviewed.