N Dissociation vs Reversible 1,2-Methyl Migration in PCP Cobalt(I) Complexes in the Stereoselective Isomerization () of Allyl Ethers.

With growing efforts pushing toward sustainable catalysis, using earth-abundant metals has become increasingly important. Here, we present the first examples of cobalt PCP pincer complexes that demonstrate dual stereoselectivity for allyl ether isomerization. While the cationic cobalt complex [((PCP)Co)-μ-N][BAr ] () mainly favors the -isomer of the enol ether, the corresponding methyl complex [(PCP)CoMe] () mostly gives the -isomer.

CuH-Catalyzed Regio- and Enantioselective Formal Hydroformylation of Vinyl Arenes.

A highly enantioselective formal hydroformylation of vinyl arenes enabled by copper hydride (CuH) catalysis is reported. Key to the success of the method was the use of the mild Lewis acid zinc triflate to promote the formation of oxocarbenium electrophiles through the activation of diethoxymethyl acetate. Using the newly developed protocol, a broad range of vinyl arene substrates underwent efficient hydroacetalization reactions to provide access to highly enantioenriched α-aryl acetal products in good yields with exclusively branched regioselectivity.

Formation of distinct iron hydrides mechanistic divergence in directed C-H Bond activation of aryl ketones, esters and amides.

Directing groups play an important role in controlling the selectivity of C-H bond activation. Here we demonstrate that for iron, the nature of the directing group (, ketone, ester, or amide) influences the C-H activation process. In this study the C-H bond activation step either occurs with or without the assistance of the directing group resulting in distinct - and -isomers of the corresponding iron hydride.

Manganese-Catalyzed Hydroboration of Terminal Olefins and Metal-Dependent Selectivity in Internal Olefin Isomerization-Hydroboration.

In the past decade, the use of earth-abundant metals in homogeneous catalysis has flourished. In particular, metals such as cobalt and iron have been used extensively in reductive transformations including hydrogenation, hydroboration, and hydrosilylation. Manganese, on the other hand, has been considerably less explored in these reductive transformations.

Z-Selective Alkyne Functionalization Catalyzed by a -Dihydride N-Heterocyclic Carbene (NHC) Iron Complex.

The -selective functionalization of terminal alkynes is a useful transformation in organic chemistry and mainly catalyzed by noble metals. Here, we present the -selective hydroboration of terminal alkynes catalyzed by a stable -dihydride iron complex [(PCP)Fe(H)N)] (). Overall, the reaction occurs at room temperature and provides near quantitative yields of the -vinylboronate ester.

Facile H/D Exchange at (Hetero)Aromatic Hydrocarbons Catalyzed by a Stable Trans-Dihydride N-Heterocyclic Carbene (NHC) Iron Complex.

Earth-abundant metal pincer complexes have played an important role in homogeneous catalysis during the last ten years. Yet, despite intense research efforts, the synthesis of iron PCP pincer complexes has so far remained elusive. Here we report the synthesis of the first PCP functionalized iron complex [(PCP)FeCl] () and the reactivity of the corresponding -dihydride iron(II) dinitrogen complex [(PCP)Fe(H)N)] ().