A Cobalt Catalyst Permits the Direct Hydrogenative Synthesis of 1H-Perimidines from a Dinitroarene and an Aldehyde.

A new sustainable catalytic reaction, the synthesis of 1H- perimidines from a dinitroarene and an aldehyde in the presence of H2 , was achieved. An earth-abundant metal catalyst was developed to permit the efficient, highly chemoselective, and consecutive hydrogenation of dinitroarenes. The catalyst was reusable and easy to handle. The use of a specific Co complex and its pyrolysis at a certain temperature was crucial to achieve high activity for the complex organic transformation. Benzylic and aliphatic aldehydes could undergo the hydrogenative condensation, and many functional groups, including hydrogenation-sensitive examples such as iodo aryl, nitrile, olefin, and alkyne groups, were tolerated.

Catalytic condensation for the formation of polycyclic heteroaromatic compounds.

The conservation of our global element resources is a challenge of the utmost urgency. Since aliphatic and aromatic alcohols are accessible from abundant indigestible kinds of biomass, first and foremost lignocellulose, the development of novel chemical reactions converting alcohols into important classes of compounds is a particularly attractive carbon conservation and CO2-emission reduction strategy. Herein, we report the catalytic condensation of phenols and aminophenols or aminoalcohols. The overall reaction of this synthesis concept proceeds via three steps: hydrogenation, dehydrogenative condensation and dehydrogenation. Reusable catalysts recently developed in our laboratory mediate these reactions highly efficient. The scope of the concept is exemplarily demonstrated by the synthesis of carbazoles, quinolines and acridines, the structural motifs of which figure prominently in many important natural products, drugs and materials.

A Reusable Co Catalyst for the Selective Hydrogenation of Functionalized Nitroarenes and the Direct Synthesis of Imines and Benzimidazoles from Nitroarenes and Aldehydes.

The use of abundantly available transition metals in reactions that have been preferentially mediated by rare noble metals, for example, hydrogenations, is a desirable aim in catalysis and an attractive strategy for element conservation. The observation of novel selectivity patterns with such inexpensive metal catalysts is especially appealing. Herein, we report a novel, robust, and reusable cobalt catalyst that permits the selective hydrogenation of nitroarenes in the presence of highly hydrogenation-sensitive functional groups, as well as the direct synthesis of imines from nitroarenes and aldehydes or ketones in the presence of such substituents. Furthermore, we introduce the first base-metal-mediated direct synthesis of benzimidazoles from nitroarenes and aldehydes. Functional groups that are easy to hydrogenate are again well tolerated.

Single-catalyst high-weight% hydrogen storage in an N-heterocycle synthesized from lignin hydrogenolysis products and ammonia.

Large-scale energy storage and the utilization of biomass as a sustainable carbon source are global challenges of this century. The reversible storage of hydrogen covalently bound in chemical compounds is a particularly promising energy storage technology. For this, compounds that can be sustainably synthesized and that permit high-weight% hydrogen storage would be highly desirable. Herein, we report that catalytically modified lignin, an indigestible, abundantly available and hitherto barely used biomass, can be harnessed to reversibly store hydrogen. A novel reusable bimetallic catalyst has been developed, which is able to hydrogenate and dehydrogenate N-heterocycles most efficiently. Furthermore, a particular N-heterocycle has been identified that can be synthesized catalytically in one step from the main lignin hydrogenolysis product and ammonia, and in which the new bimetallic catalyst allows multiple cycles of high-weight% hydrogen storage.