Combined KOH/BEt3 Catalyst for Selective Deaminative Hydroboration of Aromatic Carboxamides for Construction of Luminophores.

The selective catalytic C-N bond cleavage of amides into value-added amine products is a desirable but challenging transformation. Molecules containing iminodibenzyl motifs are prevalent in pharmaceutical molecules and functional materials. Here we established a combined KOH/BEt3 catalyst for deaminative hydroboration of acyl-iminodibenzyl derivatives, including nonheterocyclic carboxamides, to the corresponding amines. This novel transition-metal-free methodology was also applied to the construction of Clomipramine and luminophores.

Ru-Catalyzed ortho-Selective Diborylation of 2-Arylpyridines toward the Construction of π-Conjugated Functions.

A ruthenium catalytic ortho-C-H diborylation of 2-arylpyridine derivatives, including challenging 2-phenoxypyridine functions, using a remarkably low catalyst loading and a low-cost and bench-stable boron source, has been developed. The novel strategy shows high activity with excellent selectivity and may offer a versatile and green alternative to currently employed high loadings of noble metals or extra additives for the selective borylations.

Ru-Catalyzed Selective C(sp3 )-H Monoborylation of Amides and Esters.

A ruthenium-catalyzed method has been developed for the C(sp3 )-H monoborylation of various unactivated alkyl and aryl amides and challenging esters, with a low-cost and bench-stable boron source, providing boronates with exclusive selectivity, high efficiency, and high turnover number (up to 8900). This novel strategy may offer a versatile and environmentally friendly alternative to current methods for selective C(sp3 )-H borylation that employ even more expensive metals, such as iridium and rhodium.

Sodium Triethylborohydride-Catalyzed Controlled Reduction of Unactivated Amides to Secondary or Tertiary Amines.

The first transition-metal-free catalytic protocol for controlled reduction of amide functions using cheap and bench-stable hydrosilanes as reducing agents has been established. By altering the hydrosilane and solvent, the new method enables the selective cleavage of unactivated C-O bonds in amides and allows the C-N bonds to selectively break via the deacylated cleavage. Overall, this novel process may offer a versatile alternative to current methodologies employing stoichiometric metal systems for the controlled reduction of carboxamides.

Environmentally Benign, Base-Promoted Selective Amination of Polyhalogenated Pyridines.

An environmentally benign, highly efficient, and base-promoted selective amination of various polyhalogenated pyridines including the challenging pyridine chlorides to 2-aminopyridine derivatives using water as solvent has been developed. Featuring the use of the new method, the reaction is extended to the transformation on a large scale. Mechanistic studies indicate that the pathway involving a base aidant dissociation of N,N-dimethylformamide to generate dimethylamine is likely.

A BEt3-Base Catalyst for Amide Reduction with Silane.

Reported herein is the development of a simple but practical catalytic system for the selective reduction of amides with hydrosilane or hydrosiloxane. Low-cost and readily available triethylborane (1.0 M in THF), in combination with a catalytic amount of an alkali metal base, was found to catalyze the reduction of all three amide classes (tertiary, secondary, and primary amides) to form amines under mild conditions. In addition, the selective transformation of secondary amides to aldimines and primary amides to nitriles can also be achieved by using a proper combination of BEt3 and base. The scope of these BEt3-base-catalyzed amide hydrosilylation reactions has been explored in depth. Preliminary results of mechanistic studies suggest a modified Piers' silane Si-H···B activation mode wherein the hydride abstraction by BEt3 is promoted by the coordination of an alkoxide or hydroxide anion to the Si center.

An Additive-Free, Base-Catalyzed Protodesilylation of Organosilanes.

We report an additive-free, base-catalyzed C-, N-, O-, and S-Si bond cleavage of various organosilanes in mild conditions. The novel catalyst system exhibits high efficiency and good functional group compatibility, providing the corresponding products in good to excellent yields with low catalyst loadings. Overall, this transition-metal-free process may offer a convenient and general alternative to current employing excess bases, strong acids, or metal-catalyzed systems for the protodesilylation of organosilanes.

A Pincer Ruthenium Complex for Regioselective C-H Silylation of Heteroarenes.

A pincer Ru(II) catalyst for the highly efficient undirected silylation of O- and S-heteroarenes with (TMSO)2MeSiH and Et3SiH is described, producing heteroarylsilanes with exclusive C2-regioselectivity, good functional-group tolerance, and high turnover numbers (up to 1960). The synthetic utility of the silylated products is demonstrated by Pd-catalyzed Hiyama-Denmark cross-coupling under mild conditions. One-pot, two-step silylation and coupling procedures have been also developed.

Selective catalytic transfer dehydrogenation of alkanes and heterocycles by an iridium pincer complex.

Catalytic alkane dehydrogenation is a reaction with tremendous potential for application. We describe a highly active PSCOP-pincer iridium catalyst for transfer dehydrogenation of cyclic and linear alkanes. The dehydrogenation of linear alkanes occurs under relatively mild conditions with high regioselectivity for α-olefin formation. In addition, the catalyst system is very effective in the dehydrogenation of heterocycles to form heteroarenes and olefinic products.

Iridium-catalyzed selective α-alkylation of unactivated amides with primary alcohols.

The first α-alkylation of unactivated amides with primary alcohols is described. An effective and robust iridium pincer complex has been developed for selective α-alkylation of tertiary and secondary acetamides involving a "borrowing hydrogen" methodology. The method is compatible with alcohols bearing various functional groups. This presents a convenient and environmentally benign protocol for α-alkylation of amides.