Palladium-Catalyzed Site-Selective Arylation of α,β-Unsaturated Carbonyl Compounds through a Ligand-Controlled Strategy

Abstract

Palladium-catalyzed direct arylation of α,β-unsaturated carbonyl compounds is an efficient and attractive strategy to access arylated α,β-unsaturated carbonyl compounds through the construction of carbon–carbon bonds. This reaction has several challenges, especially in terms of the control of regioselectivity between α- and γ-arylation and the selectivity for monoarylation and multiple arylation. Herein, we discuss the recent development of γ-arylation of α,β-unsaturated carbonyl compounds and present the ligand-controlled, site-selective α- and γ-arylation of α,β-unsaturated carbonyl ketones with (hetero)aryl halides. The site selectivity of the reaction is switchable by simply changing the phosphine ligand.1 Introduction2 Reaction Development and Mechanistic Investigation3 Conclusion and Outlook

Indomuscone-Based Sterically Encumbered Phosphines as Ligands for Palladium-Catalyzed Reactions

“…Phosphines are very active ligands for palladium-catalyzed organic reactions, which include cross-coupling reactions, hydrogenations, and hydro­(alkoxy)­formylations, , to name a few . In particular, sterically encumbered phosphines are considered privileged ligands in palladium-catalyzed reactions such as the telomerization reaction, the Buchwald–Hartwig and Suzuki cross-coupling reactions, the semi-hydrogenation reaction of alkynes, and others .…”

“…Phosphines are very active ligands for palladium-catalyzed organic reactions, which include cross-coupling reactions, 1 hydrogenations, 2 and hydro(alkoxy)formylations, 2 , 3 to name a few. 4 In particular, sterically encumbered phosphines are considered privileged ligands in palladium-catalyzed reactions such as the telomerization reaction, 5 the Buchwald–Hartwig 6 and Suzuki 7 cross-coupling reactions, the semi-hydrogenation reaction of alkynes, 8 and others. 9 The rationale behind the high catalytic activity of these phosphines with palladium lies, on one hand, on the protection of the metal site during the catalytic cycle, which avoids typical palladium deactivation processes such as reduction or aggregation, and, on the other hand, on the formation of ipso carbon-palladium bonds that pre-activates the catalytic site for reagent coordination.…”