Transition-metal-catalyzed cross-coupling reactions have been well-established as indispensable tools in modern organic synthesis. One of the major research goals in cross-coupling area is expanding the scope of the coupling partners. In the past decade, diazo compounds (or their precursors N-tosylhydrazones) have emerged as nucleophilic cross-coupling partners in C–C single bond or C═C double bond formations in transition-metal-catalyzed reactions. This type of coupling reaction involves the following general steps. First, the organometallic species is generated by various processes, including oxidative addition, transmetalation, cyclization, C–C bond cleavage, and C–H bond activation. Subsequently, the organometallic species reacts with the diazo substrate to generate metal carbene intermediate, which undergoes rapid migratory insertion to form a C–C bond. The new organometallic species generated from migratory insertion may undergo various transformations. This type of carbene-based coupling has proven...

Transition-Metal-Catalyzed Cross-Couplings through Carbene Migratory Insertion

The conservation of our element resources is a fundamental challenge of mankind. The development of alcohol refunctionalization reactions is a possible fossil carbon conservation strategy since alcohols can be obtained from indigestible and abundantly available biomass. The conservation of our rare noble metals, frequently used in key technologies such as catalysis, might be feasible by replacing them with highly abundant metals. The alkylation of amines by alcohols and related C–C coupling reactions are early examples of alcohol refunctionalization reactions. These reactions follow mostly the borrowing hydrogen or hydrogen autotransfer catalysis concept, and many 3d-metal catalysts have been disclosed in recent years. In this review, we summarize the progress made in developing Cu, Ni, Co, Fe, and Mn catalysts for C–N and C–C bond formation reactions with alcohols and amines using the borrowing hydrogen or hydrogen autotransfer concept. We expect that the findings in this field will inspire others to dev...

3d-Metal Catalyzed N- and C-Alkylation Reactions via Borrowing Hydrogen or Hydrogen Autotransfer

Herein we report the manganese-catalyzed C-C bond-forming reactions via α-alkylation of ketones, amides, and esters, using primary alcohols. β-Alkylation of secondary alcohols by primary alcohols to obtain α-alkylated ketones is also reported. The reactions are catalyzed by a ( i Pr-PNP)Mn(H)(CO)2 pincer complex under mild conditions in the presence of (catalytic) base liberating water (and H2 in the case of secondary alcohol alkylation) as the sole byproduct.

Manganese-Catalyzed α-Alkylation of Ketones, Esters, and Amides Using Alcohols

Manganese(I) complexes bearing a pyridyl-supported pyrazolyl-imidazolyl ligand efficiently catalyzed the direct β-alkylation of secondary alcohols with primary alcohols under phosphine-free conditions. The β-alkylated secondary alcohols were obtained in moderate to good yields with water formed as the byproduct through a borrowing hydrogen pathway. β-Alkylation of cholesterols was also effectively achieved. The present protocol provides a concise atom-economical method for C–C bond formation from primary and secondary alcohols.

Manganese-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols under Phosphine-Free Conditions

Phosphine free Mn-complex catalysed dehydrogenative C–C and C–heteroatom bond formation: a sustainable approach to synthesize quinoxaline, pyrazine, benzothiazole and quinoline derivatives

Substituent Effect on the Catalytic Activity of Ruthenium(II) Complexes Bearing a Pyridyl-Supported Pyrazolyl-Imidazolyl Ligand for Transfer Hydrogenation of Ketones

Potassium tert-butoxide-promoted acceptorless dehydrogenation of N-heterocycles was efficiently realized for the generation of N-heteroarenes and hydrogen gas under transition-metal-free conditions. In the presence of KOtBu base, a variety of sixand five-membered N-heterocyclic compounds efficiently underwent acceptorless dehydrogenation to afford the corresponding N-heteroarenes and H2 gas in o-xylene at 140 °C. The present protocol provides a convenient route to aromatic nitrogen-containing compounds and H2 gas.

Tingting Liu

Papers

Manganese-Catalyzed β-Alkylation of Secondary Alcohols with Primary Alcohols under Phosphine-Free Conditions

Substituent Effect on the Catalytic Activity of Ruthenium(II) Complexes Bearing a Pyridyl-Supported Pyrazolyl-Imidazolyl Ligand for Transfer Hydrogenation of Ketones

Potassium tert‐Butoxide‐Promoted Acceptorless Dehydrogenation of N‐Heterocycles

A Versatile Ru(II)-NNP Complex Catalyst for the Synthesis of Multisubstituted Pyrroles and Pyridines

Exceptionally Active Assembled Dinuclear Ruthenium(II)-NNN Complex Catalysts for Transfer Hydrogenation of Ketones