A Barbier-type Cp2TiCl2-mediated (10 mol %) photoredox allylation of aldehydes under irradiation with visible light (blue light-emitting diodes (LEDs), 450 nm) and in the presence of an organic dye (3DPAFIPN, 5 mol %) with allylbromides is described.

Salen ligands are a class of Schiff bases simply obtained through condensation of two molecules of a hydroxyl-substituted aryl aldehyde with an achiral or chiral diamine. The prototype salen, or N,N′-bis(salicylidene)ethylenediamine has a long history, as it was first reported in 1889, and immediately, some of its metal complexes were also described. Now, the salen ligands are a class of N,N,O,O tetradentate Schiff bases capable of coordinating many metal ions. The geometry and the stereogenic group inserted in the diamine backbone or aryl aldehyde backbone have been utilized in the past to efficiently transmit chiral information in a variety of different reactions. In this review we will summarize the important and recent achievements obtained in stereocontrolled reactions in which Al(salen) metal complexes are employed. Several other reviews devoted to the general applications and synthesis of chromium and other metal salens have already been published.

Here we report the application of dual nickel/photoredox catalysis to the allylation of aliphatic, aromatic and heteroaromatic aldehydes by using commercially available reagents.

The use of organic dyes to promote organic reactions by photoredox catalysis is continuosly expanding, and was recently reviewed by Nicewicz. The synthesis of new dyes, their application in flow...

Here we report a practical, highly enantioselective photoredox allylation of aldehydes mediated by chiral nickel complexes with commercially available allyl acetate as the allylating agent. The methodology allows the clean stereoselective allylation of aldehydes in good to excellent yields and up to 93 % e.e. using a catalytic amount of NiCl2(glyme) in the presence of the chiral aminoindanol‐derived bis(oxazoline) as the chiral ligand. The photoredox system is constituted by the organic dye 3DPAFIPN and a Hantzsch's ester as the sacrificial reductant. The reaction proceeds under visible‐light irradiation (blue LEDs, 456 nm) at 8–12 °C. Compared to other published procedures, no metal reductants (such as Zn or Mn), additives (e.g. CuI) or air‐sensitive Ni(COD)2 are necessary for this reaction. Accurate DFT calculations and photophysical experiments have clarified the mechanistic picture of this stereoselective allylation reaction.