Copper(I) hydride-catalyzed asymmetric hydrosilylation of heteroaromatic ketones

Palladium-catalyzed enantioselective carbonylation reactions

Carbonylation, one of the most powerful approaches to the preparation of carbonylated compounds, has received significant attention from researchers active in various fields. Indeed, impressive progress has been made on this subject over the past few decades. Among the various types of carbonylation reactions, asymmetric carbonylation is a straightforward methodology for constructing chiral compounds. Although rhodium-catalyzed enantioselective hydroformylations have been discussed in several elegant reviews, a general review on palladium-catalyzed asymmetric carbonylations is still missing. In this review, we summarize and discuss recent achievements in palladium-catalyzed asymmetric carbonylation reactions. Notably, this review’s contents are categorized by reaction type.

Copper-Catalyzed Asymmetric Reductions of Aryl/Heteroaryl Ketones under Mild Aqueous Micellar Conditions

Enantioselective syntheses of nonracemic secondary alcohols have been achieved in an aqueous micellar medium via copper-catalyzed (Cu(OAc)₂·H₂O/(R)-3,4,5-MeO-MeO-BIPHEP) reduction of aryl/heteroaryl ketones. This methodology serves as a green protocol to access enantio-enriched alcohols under mild conditions (0-22 °C) using a base metal catalyst, together with an inexpensive, innocuous, and convenient stoichiometric hydride source (PMHS). The secondary alcohol products are formed in good to excellent yields with ee values greater than 90%.

Silicon Industry Waste Polymethylhydrosiloxane-Mediated Benzotriazole Ring Cleavage: A Practical and Green Synthesis of Diverse Benzothiazoles

A green modification has been introduced to the synthesis of benzothiazoles by using polymethylhydrosiloxane (PMHS) for successive steps of benzotriazole ring cleavage and cyclization, an approach which was previously developed in our lab by the use of n-Bu₃SnH. The use of the silicone industry byproduct PMHS makes this protocol a cost-effective and nontoxic one and thus may be considered for the industrial importance.

Bio-based Catalysts from Biomass Issued after Decontamination of Effluents Rich in Copper—an Innovative Approach towards Greener Copper-based Catalysis

The abundance of Cu-contaminated effluents and the serious risk of contamination of the aquatic systems combine to provide strong motivating factors to tackle this environmental problem. The treatment of polluted effluents by rhizofiltration and biosorption is an interesting ecological alternative. Taking advantage of the remarkable ability of the selected plants to bioconcentrate copper into roots, these methods have been exploited for the decontamination of copperrich effluents. Herein, we present an overview on the utility of the resulted copper-rich biomass for the preparation of novel bio-sourced copper-based catalysts for copper-mediated reactions: from the bioaccumulation of copper in plant, to the preparation and full analysis of the new Eco-Cu catalysts, and their application in selected key reactions. The hydrolysis of a thiophosphate, an Ullmanntype coupling leading to N- and O-arylated compounds, and a CuAAC “click” reaction, all performed under green and environmentally friendly conditions, will be described.

Palladium-catalyzed regio- and enantioselective hydroesterification of aryl olefins with CO gas

An effective Pd-catalyzed regio- and enantioselective hydroesterification of aryl olefins with CO gas is described.

Manganese-Catalyzed Asymmetric Hydrosilylation of Aryl Ketones

We disclose the synthesis of a series of manganese complexes of chiral iminopyridine oxazoline ligands and their application in the first manganese-catalyzed asymmetric ketone hydrosilylations. The most sterically hindered manganese catalyst bearing two CH(Ph)₂ groups at the 2,6-ortho positions of the imino aryl ring and a tBu group on the oxazoline ring furnishes the secondary alcohols in high enantioselectivities and yields.

Palladium-Catalyzed Highly Regio- and Enantioselective Hydroesterification of Aryl Olefins with Phenyl Formate

An effective Pd-catalyzed regio- and enantioselective hydroesterification of aryl olefins with phenyl formate is described. A variety of phenyl 2-arylpropanoates can be obtained in good yields with high b/l ratios and ee's without using toxic CO gas.

Pd-Catalyzed regioselective hydroesterification of 2-allylphenols to seven-membered lactones without external CO gas

Effective Pd-catalyzed regioselective hydroesterification of 2-allylphenols with phenyl formate is described.

A palladium-catalyzed enantioselective hydroesterification of alkenylphenols with phenyl formate. A facile approach to optically active dihydrocoumarins

An effective palladium-catalyzed enantioselective hydroesterification of alkenylphenols with phenyl formate as a CO source is described.

Iron-catalyzed asymmetric hydrosilylation of ketones

Iron complexes of chiral iminopyridine-oxazoline (IPO) ligands effectively catalyze asymmetric hydrosilylation of aryl ketones.

Metal free chemoselective reduction of α-keto amides using TBAF as catalyst

Metal and ligand free chemoselective reduction of keto group and complete reduction of the both keto and amide groups of α-keto amide with hydrosilanes using tetrabutylammoniumflouride (TBAF) as catalyst have been accomplished. This methodology affords an efficient and economic route for the synthesis of biologically important α-hydroxy amides and β-amino alcohols.

Chemoselective reduction of α-keto amides using nickel catalysts

Ni-catalysts are used for the first time to synthesize α-hydroxy amides and β-amino alcohols from α-keto amides by chemoselective and complete reduction using hydrosilanes.

A palladium-catalyzed regioselective hydroesterification of alkenylphenols to lactones with phenyl formate as CO source

An effective Pd(OAc)2-PPh3 catalyzed hydroesterification of alkenylphenols with phenyl formate as CO surrogate is described. A variety of lactones are obtained in generally high yields with high regioselectivities. In one case, 76% ee is obtained with a chiral ligand.