Photoinduced Platinum-Catalyzed Reductive Allylation of α-Diketones with Allylic Carbonates.

A unique process for the photoinduced platinum-catalyzed reductive allylation of α-diketones with allylic carbonates has been developed. This allylation reaction was found to proceed selectively at the more electron-deficient carbonyl group of the diketone to afford an α-keto homoallylic alcohol. Such products could be further derivatized by transformation of the remaining carbonyl group. A mechanistic investigation suggests that a ketyl radical generated in response to photoirradiation reacts with a (π-allyl)platinum complex to form a C-C bond.

Boron-Catalyzed Michael Reaction of Donor-Acceptor Carboxylic Acid Pairs Enabling Direct Synthesis of 1,5-Dicarboxylic Acids.

A boron-catalyzed Michael reaction using pairs of carboxylic acids was developed. The reaction occurs through dual activation of the two substrates by a boron catalyst, which facilitates boron enolate formation from the donor carboxylic acid with simultaneous activation of the α,ß-unsaturated carboxylic acid as the acceptor. α-Aryl and α-alkenyl carboxylic acids were applicable as donors. The versatility and utility of this reaction were demonstrated by the direct use of pharmaceuticals as donor carboxylic acids.

Continuous-Flow Catalysis Using Phosphine-Metal Complexes on Porous Polymers: Designing Ligands, Pores, and Reactors.

Continuous-flow syntheses using immobilized catalysts can offer efficient chemical processes with easy separation and purification. Porous polymers have gained significant interests for their applications to catalytic systems in the field of organic chemistry. The porous polymers are recognized for their large surface area, high chemical stability, facile modulation of surface chemistry, and cost-effectiveness. It is crucial to immobilize transition-metal catalysts due to their difficult separation and high toxicity. Supported phosphine ligands represent a noteworthy system for the effective immobilization of metal catalysts and modulation of catalytic properties. Researchers have been actively pursuing strategies involving phosphine-metal complexes supported on porous polymers, aiming for high activities, durabilities, selectivities, and applicability to continuous-flow systems. This review provides a concise overview of phosphine-metal complexes supported on porous polymers for continuous-flow catalytic reactions. Polymer catalysts are categorized based on pore sizes, including micro-, meso-, and macroporous polymers. The characteristics of these porous polymers are explored concerning their efficiency in immobilized catalysis and continuous-flow systems.