Cobalt-Catalyzed Regioselective para-Amination of Azobenzenes via Nucleophilic Aromatic Substitution of Hydrogen

The metal-catalyzed nucleophilic aromatic substitution of hydrogen (S_NArH) via coordination of the substituent on the aromatic ring to the metal catalyst, in terms of reactivity, substrate type, and reaction selectivity, complements the transition metal-catalyzed C-H functionalization that proceeds via C-H metalation but remains an elusive target. Described herein is the development of an unprecedented cobalt-catalyzed para-selective amination of azobenzenes, which is essentially a metal-promoted S_NArH process as revealed by Hammett analysis, thus illustrating the concept that coordination of the substituent on the arene ring to the metal catalyst may result in electrophilic activation of the arene ring toward S_NArH. This cobalt-catalyzed protocol allows the use of a variety of both aliphatic amines and anilines as aminating reagents, tolerates electronically diverse substituents of azobenzene, and furnishes the corresponding products in good yields with a regiospecific selectivity for para-amination.

Radical Esterification of Unactivated Alkenes Using Formate as Carbonyl Source

In recent years, methyl formate has received considerable attention as an ideal and green C1 building block to synthesize carboxylic esters. However, examples of a one-step route to esters with one-carbon elongation using methyl formate as a source of methoxycarbonyl radical are still rare. Herein, we present peroxide-induced radical carbonylation of N-(2-methylallyl)benzamides with methyl formate as the precursor of methoxycarbonyl radical and RuCl₃ as catalyst, affording a series of biologically valuable 4-[(methoxycarbonyl)methyl]-3,4-dihydroisoquinolinones with good tolerance and insensitivity to moisture in one pot under simple and mild conditions.

Ruthenium-catalysed domino hydroformylation–hydrogenation–esterification of olefins

Aliphatic esters are made easily from acetic acid, olefins, and synthesis gas. In the presence of ruthenium–phosphine complexes novel domino-hydroformylation–hydrogenation–esterification proceeds in moderate to good yields.

Ruthenium-catalysed hydroxycarbonylation of olefins

A ruthenium-catalysed hydroxycarbonylation of olefins. We report a ruthenium-catalysed hydroxycarbonylation of unfunctionalized olefins.

Creation of Novel Toxic Gas Surrogates and the Development of Safe and Facile Catalytic Reactions

The use of toxic gas surrogates in organic reactions instead of the gas itself contributes to enhancing the safety, practicality, and efficiency of the reactions involved. Our efforts toward the creation of toxic gas surrogates and the development of a series of catalytic reactions using these surrogates are described. Improvements in substrate scope during the hydroesterification of alkenes using formates facilitated by the Ru-imidazole catalyst system provided the opportunity to discover that phenyl formate is a useful carbon monoxide (CO) surrogate for the generation of CO and phenol under weakly basic conditions. This discovery triggered the development of highly reactive but stable CO surrogates and a variety of Pd-catalyzed carbonylative transformations. N-Formylsaccharin facilitated the use of additional nucleophiles in carbonylation reactions that provided access to a variety of carbonyl compounds. Detailed experimental and theoretical mechanistic studies into the generation of CO from phenyl formate suggest that CO generation proceeds via a concerted E2 α-elimination. Furthermore, a known surrogate of sulfur dioxide was applied for the first time to the selective syntheses of cyclic sulfonamides and sulfinamides, confirming that the surrogate operates as an "S=O" source. Notably, the reactions described herein are scalable and can be performed without the use of external toxic gases and specialized reaction vessels; they are easy and simple to perform and demonstrate enormous potential for industrial application.

An effective approach to aryl-substituted propanoic acids via the Pd-catalyzed hydrocarboxylation of stilbenes

An effective Pd(0)-catalyzed hydrocarboxylation of substituted stilbenes with formic acid and HCOOPh is described. A variety of aryl-substituted propanoic acids are obtained in good yields without using external 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.

A catalytic hydroesterification process using HCO2Na, Ru3(CO)12 and alcohols for the preparation of ester modified polybutadienes

A chelation-assisted hydroesterification method for the preparation of modified polybutadiene was developed.