Anti-Selective Carbosilylation: Nickel-Catalyzed Multicomponent Reaction of Solid Me3SiZnI.

The stereodefined and highly substituted vinylsilanes are essential building blocks for constructing complex organic molecules. Transition metal-mediated silylmetalation of alkynes was developed to overcome the limitations of conventional hydrosilylations; however, a very limited study was carried out to utilize transient vinylmetal species in cross-coupling reactions. Moreover, they produce syn-adduct, and the anti-selective cross-coupling is still unknown and highly desired. Silylzinc reagents are highly functional group tolerant, however, their synthesis from pyrophoric silyllithium and dissolved lithium salts hampers cross-coupling reactions. Our novel solid silylzinc reagents circumvent these constraints are employed in the anti-selective synthesis of vinylsilanes via a multi-component reaction involving Me3SiZnI, terminal alkynes, and activated alkyl halides. An intensive computational and experimental investigation of the mechanism reveals an equilibrium between the intermediate syn- and anti-adducts; the greater barrier at the single electron reduction of alkyl halides and the thermodynamic stability of the Ni(III) adduct determine the anti-selectivity.

Photoredox-Ni Dual Catalysis: Chelation-Free Hydroacylation of Terminal Alkynes.

Hydroacylation of alkynes is undoubtedly the simplest and most atom-efficient approach for the synthesis of enones with diverse synthetic applications. Despite significant progress in hydroacylations, no hydroacylations exist that make use of aldehydes without a chelating group, especially when combined with terminal alkynes. Here we report a synergistic nickel-photocatalytic system that allows for the highly regio- and stereoselective hydroacylation of unactivated aldehydes and alkynes in milder conditions without the use of chelating groups.

Application of metal-based reagents and catalysts in microstructured flow devices.

Over the years, organic synthesis has witnessed several improvements through the development of new chemical transformations or more efficient reagents for known processes. Likewise, technological advances, aiming at speeding up reactions and facilitating their work-up, have established themselves in academic as well as in industrial laboratories. In this Minireview, we highlight very recent developments in flow chemistry, focusing on organometallic reagents and catalysts. First, we describe reactions with homogeneous catalysts immobilized on different support materials using the concept of packed bed reactors. In the last chapter, we will discuss applications that utilize organometallic reagents.

Combination of perfluoroalkyl and triazole moieties: a new recovery strategy for TEMPO.

The attachment of multiple triazole moieties and perfluoroalkyl chains to TEMPO promotes emulsion formation in dichloromethane/water, giving a highly active and easily recoverable catalyst for the oxidation of alcohols.