Rhodium‐Catalyzed Addition of Aryl Boronic Acids to 2,2‐Disubstituted Malononitriles

• Published in: Angewandte Chemie 2017-06, Vol.129 (24), p.7103-7106
• Main Authors: Malapit, Christian A., Caldwell, Donald R., Luvaga, Irungu K., Reeves, Jonathan T., Volchkov, Ivan, Gonnella, Nina C., Han, Zhengxu S., Busacca, Carl A., Howell, Amy R., Senanayake, Chris H.
• Format: Article
• Language: English
• Subjects: Acids; Aromatic compounds; Boronsäuren; Catalysis; Chemistry; Collapse; Homogene Katalyse; Imines; Rhodium; Sulfinimine; β-Ketonitrile
• ISSN: 0044-8249; 1521-3757
• DOI: 10.1002/ange.201703471

β‐Ketonitriles bearing a quaternary carbon at the 2‐position were prepared through Rh‐catalyzed addition of aryl boronic acids to 2,2‐disubstituted malononitriles. In contrast to the previously described transnitrilative cyanation of aryl boronic acids with dialkylmalononitriles, the present reaction avoids retro‐Thorpe collapse of the intermediate addition product through the use of a milder base. The reaction was amenable to a variety of aryl boronic acids and disubstituted malononitriles, providing a diverse array of β‐ketonitriles. The products could be further derivatized to valuable chiral α,α‐disubstituted‐β‐aminonitriles through addition reactions to the corresponding N‐tert‐butanesulfinyl imines. Eine Frage der Base: Unter Rh‐Katalyse addieren Arylboronsäuren an 2,2‐disubstituierte Malononitrile und bilden β‐Ketonitrile. Wird statt Cs2CO3, das eine Nitrilübertragung vermittelt, ein Protonenschwamm als Base eingesetzt, so lässt sich die Retro‐Thorpe‐Fragmentierung der intermediären β‐Iminonitrile verhindern. Die β‐Ketonitril‐Produkte lieferten durch hoch diastereoselektive Additionen die entsprechenden N‐tert‐Butansulfinylimine.