Novel Chelating Phosphonite Ligands: Syntheses, Structures, and Nickel-Catalyzed Hydrocyanation of Olefins

• Published in: Organometallics Vol. 27; no. 10; pp. 2189 - 2200
• Main Authors: Göthlich, Alexander P. V, Tensfeldt, Marcus, Rothfuss, Helmut, Tauchert, Michael E, Haap, Dagmar, Rominger, Frank, Hofmann, Peter
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 26.05.2008; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Physical Sciences; Science & Technology; KETONES; DIPHOSPHINE LIGANDS; BITE ANGLES; ISOMERIZATION; ASYMMETRIC HYDROGENATION; BULKY PHOSPHITE; RHODIUM COMPLEXES; 2-METHYL-3-BUTENENITRILE; CONJUGATE ADDITION; HYDROFORMYLATION
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om701140c

A series of sterically tuned chelating bisarylphosphonite ligands with a cis-1,2-(bi)cycloalkane spacer and cyclic phosphonite moieties was synthesized. The spacer as well as the phosphacycles were modified to investigate their influence in the nickel-catalyzed hydrocyanation of styrene and 1,3-butadiene and the isomerization of 2-methyl-3-butenenitrile. NMR studies detect only catalytically active (P∩P)Ni(COD) species and no hints of the formation of catalytically inactive dibisphosphonite complexes (P∩P)2Ni are found. In the hydrocyanation of styrene, these catalysts are highly active (93% conversion) and highly regioselective (99.9% iso) at moderate catalyst concentrations (1 mol %). They also proved to be very active in the hydrocyanation of butadiene with turnover numbers of 644 and turnover frequencies of 426 h−1 at low catalyst concentrations (0.1 mol %). Moreover, they very efficiently catalyze the isomerization of 2-methyl-3-butenenitrile to the linear 3-pentenenitrile.