Palladium‐ and Iridium‐Catalyzed Deracemization of Allylic Oxygen Compounds with Oxygen Nucleophiles

Abstract

Allylic oxygen compounds (AOCs) are an important class of versatile building blocks in natural and non‐natural product synthesis. Catalytic in‐situ deracemization is an attractive means for their enantioselective synthesis. Particularly attractive is the deracemization of AOCs through transition metal‐catalyzed dynamic kinetic asymmetric transformation (DYKAT) with oxygen nucleophiles (ONus). This review describes pertinent aspects of the palladium‐catalyzed DYKAT of racemic allylic carboxylates, vinyl oxiranes and vinyl dioxolanones with carboxylates, hydrogen carbonate, alcohols, phenols, oximes, diosphenols and water and the iridium‐catalyzed DYKAT of racemic allylic alcohols, imidates and carboxylates with alcohols and carboxylic acids. Included in the discussion is the palladium‐catalyzed desymmetrization of meso‐cycloalkene bis(carboxylates) with hydrogen carbonate. While Trost's bisphosphinobenzamides, Zhou's spiro‐phosphoramidite and Feringa's BINOL‐phosphoramidite are highly efficient ligands in palladium‐catalyzed DYKAT, Carreira‐Dorta's BINOL‐phosphoramidite‐olefin is an excellent ligand in iridium‐catalyzed DYKAT. This review also discusses mechanistic and structural aspects of η3‐allylpalladium‐bisphosphinobenzamide and η3‐allyliridium‐BINOL‐phosphoramidite‐olefin complexes and of the corresponding catalysts.

N1-Allylation of Arylhydrazines via a Palladium-Catalyzed Allylic Substitution

“…It is well-known that the palladium-catalyzed allylic substitution reaction and the asymmetric version with various nucleophiles, including active carbon nucleophiles, nitrogen nucleophiles, oxygen nucleophiles, and so on, are some of the most powerful tools for the synthesis of allylic derivatives through the carbon–carbon or carbon–heteroatom bond construction in organic synthesis . However, as a special type of nitrogen nucleophile, the use of arylhydrazines in palladium-catalyzed allylic substitution reactions has not been reported yet .…”