Ruthenium-Catalyzed Reactions for Organic Synthesis.

Chemical and biochemical transformations in ionic liquids

Nitrogen heterocycles are abundant in natural products and pharmaceuticals. An emerging interest among synthetic chemists is to use C-H functionalization to construct the nitrogen-containing core of these heterocycles. The following article will provide a brief overview of this concept with respect to the type of C-H bond functionalized.

http://aether.cmi.ua.ac.be/artikels/Artikels%20Gitte/Artikels/Reviews/chem%20eur%20j%202009%205874%20review%20C-H%20activation%20Lautens.pdf

Construction of nitrogen-containing heterocycles by C-H bond functionalization.

The reduction of nitro compounds to the corresponding amines is one of the most utilized catalytic processes in the fine and bulk chemical industry. The latest development of catalysts with cheap metals like Fe, Co, Ni, and Cu has led to their tremendous achievements over the last years prompting their greater application as “standard” catalysts. In this review, we will comprehensively discuss the use of homogeneous and heterogeneous catalysts based on non-noble 3d-metals for the reduction of nitro compounds using various reductants. The different systems will be revised considering both the catalytic performances and synthetic aspects highlighting also their advantages and disadvantages.

/pdf/reduction-of-nitro-compounds-using-3d-non-noble-metal-5b70ogvyef.pdf

Reduction of Nitro Compounds Using 3d-Non-Noble Metal Catalysts

The earth-abundant nanohybrids Co0/Co3O4@N-doped carbon nanotubes were fabricated via an efficient thermal condensation of d-glucosamine hydrochloride, melamine, and Co(NO3)2·6H2O. The hybrids furnish excellent catalytic activity and perfect chemoselectivity (>99%) for a wide range of substituted nitroarenes (21 examples) under relatively mild conditions. The high catalytic performance and durability is attributed to the synergistic effects between each component, the unique structure of graphene layers-coated Co0, and the electronic activation of doped nitrogen. Density functional calculations indicate that the inner Co0 core and N species on the carbon shell can significantly decrease the dissociation energies of H2, giving evidence of the ability of carbon shell in the hybrids to enable H2 activation. These results open up an avenue to design more powerful low-cost catalysts for industrial applications.

In Situ-Generated Co0-Co3O4/N-Doped Carbon Nanotubes Hybrids as Efficient and Chemoselective Catalysts for Hydrogenation of Nitroarenes

Although the use of CO as a reductant had been in the past confined to few reactions, its use in organic synthesis, especially in the reductive carbonylation of nitro aromatics and the oxidative carbonylation of aromatic amines, has increased dramatically. Since the discovery of CO-induced reduction of nitro groups, there has been a wide spread increase of interest in the application and mechanistic understanding of this reaction. In a major review published in 1988 it was noted, that in practice no studies of the mechanism of N-carbonylation of aromatic nitro compounds with alcohols leading to carbamates have been carried out. This review clearly shows a major change since that publication. Indeed, metal-catalyzed reductive carbonylation of nitro aromatics using CO as reducing agent has been in the past 10 years the subject of intense investigation both in academia and in the chemical industry. Several articles and reviews have covered the subject up to the late 1980s. The authors will concentrate on more recent literature, but sometimes older data will be used to establish an understanding of these reactions. 127 refs.

Jens Weiguny

Papers

A Review of the Selective Catalytic Reduction of Aromatic Nitro Compounds into Aromatic Amines, Isocyanates, Carbamates, and Ureas Using CO.