Recent advances in palladium-catalysed asymmetric 1,4–additions of arylboronic acids to conjugated enones and chromones

Abstract

The transition metal (palladium)-catalysed asymmetric 1,4-addition of arylboronic acids to conjugated enones belong to the most important and emerging strategies for the construction of C–C bonds in an asymmetric fashion. This review covers known catalytic systems used for this transformation. For clarity, we are using the type of ligand as a sorting criterion. Finally, we attempted to create a flowchart facilitating the selection of a suitable ligand for a given combination of enone and arylboronic acid.

Pd(II)/N,N′-Disulfonyl Bisimidazoline-Catalyzed Enantioselective Synthesis of Cyclic Quaternary Centers and Mechanistic Investigations

“…Despite these advances, the catalytic enantioselective construction of these important structural motifs has faced two major challenges: one is their congested nature and the other is how to control the required stereoselectivities in forming the new C–C bond. In this scenario, transition-metal-catalyzed asymmetric conjugate addition of aryl nucleophiles to suitable β-substituted cyclic enones offers an efficient protocol for producing chiral cyclic all-carbon quaternary stereocenters. − Among them, Pd-catalyzed asymmetric conjugate additions to cyclic enones with organoboron reagents have taken a dominant position, benefiting from their stability toward air and moisture, good functional group tolerance, and availability of the reaction, − and a variety of chiral bidentate ligands have been utilized, such as ( S )- t BuPyOx, ( R , R )-PhBOX, pyridine-hydrazone, pyridine-dihydroisoquinoline (PyDHIQ), and 1,10-phenanthroline (Scheme a). However, achieving stereocontrol with a new catalytic system together with a broad substrate scope is highly demanded to complement or surpass the existing methods.…”

Enantioselective transannular reactions by palladium-catalysed conjugate addition of aryl boronic acids

“…8 Even so, Pd( ii ) catalysis has demonstrated to be an excellent alternative to Rh( i ), for the addition of aryl boron reagents to electron-deficient olefins, showing higher turnover numbers for cyclic and acyclic enones and enals under much lower cost. 9…”