Mechanochemical Radical Transformations in Organic Synthesis

Organic synthesis has historically relied on solution-phase, polar transformations to forge new bonds. However, this paradigm is evolving, propelled by the rapid evolution of radical chemistry. Additionally, organic synthesis is witnessing a simultaneous resurgence in mechanochemistry, the formation of new bonds in the solid-state, further contributing to this shift in the status quo. The aforementioned advances in radical chemistry have predominantly occurred in the solution phase, while the majority of mechanochemical synthesis advances feature polar transformations. Herein, we discuss a rapidly advancing area of organic synthesis: mechanochemical radical reactions. Solid-state radical reactions offer improved green chemistry metrics, better reaction outcomes, and access to intermediates and products that are difficult or impossible to reach in solution. This review explores these reactions in the context of small molecule synthesis, from early findings to the current state-of-the-art, underscoring the pivotal role solid-state radical reactions are likely to play in advancing sustainable chemical synthesis.

Changing stereoselectivity and regioselectivity in copper(i)-catalyzed 5-exo cyclization by chelation and rigidity in aminoalkyl radicals: synthesis towards diverse bioactive N-heterocycles

Chelation, rigidity and carbon-radical positions in aminoalkyl precursors disturb the usual 2,4-trans diastereoselectivity and 5-exo mode in Cu(i)-catalyzed ATRC.

Recent advances of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) in photocatalytic transformations

In this review, the recent advances of the application of 1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene (4CzIPN) as a photoredox catalyst in the past three years (2016–2018) for various organic reactions are summarized.

Copper promoted radical addition/cyclization of azobisisobutyronitrile with arylacrylamides: a convenient process to synthesize 3-(2′-cyano alkyl) oxindoles

A CuI promoted radical addition/cyclization of azobisisobutyronitrile with alkenes for the preparation of 3-(2′-cyano alkyl) oxindoles was developed.

Multi-bond forming and iodo-selective base-promoted homolytic aromatic substitution

Base-promoted homolytic aromatic substitution (BHAS) has been applied as a means to effect multi-bond forming reactions.

The kinetics of carbonyl radical ring closures

Kinetic data for intramolecular homolytic substitution reactions of a series of acyl and oxyacyl radicals are reported.

The kinetics of alkyl radical ring closures at selenium: formation of selenane

Intramolecular homolytic substitution reactions of 5-(alkylseleno)pentyl radicals 4 have been investigated by competition kinetics as well as computational techniques.