A Reusable Co Catalyst for the Selective Hydrogenation of Functionalized Nitroarenes and the Direct Synthesis of Imines and Benzimidazoles from Nitroarenes and Aldehydes. Issue 48 (31st October 2016)

• Record Type: Journal Article
• Authors: Schwob, Tobias; Kempe, Rhett
• Is Part Of: Angewandte Chemie international edition. Volume 55:Issue 48(2016)
• Page Start: 15175
• Page End: 15179
• Publication Date: 2016-10-31
• Subjects: benzimidazoles -- cobalt catalysis -- hydrogenation -- imines -- nitroarenes; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201608321
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: 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. Abstract : Reduce, reuse, recycle : A reusable nanocomposite cobalt catalyst was developed that is easy to synthesize and can be handled in air. It efficiently mediates the selective hydrogenation of nitroarenes, as well as the direct synthesis of imines or benzimidazoles from nitroarenes and aldehydes. Functional groups that are highly sensitive to hydrogenation are well tolerated, and the hydrogenation activity can be regenerated through temperature‐programmed reduction.