we have described the isolation of the first CNN pincer osmium complexes [OsX(CNN)P2] to display high catalytic activity and productivity in the reduction of ketones by either TH or HY (TOFand TON up to 106 h1 and 105, respectively). A high enantioselectivity (up to 98% ee) is possible in both reactions with a remarkably low catalyst loading (0.005–0.002 mol%). To the best of our knowledge, this is the first example of an osmium complex that catalyzes the asymmetric HY of ketones. Evidence for an Os-OR vs. Os-H equilibrium suggests that both these species are involved in the catalytic pathways.
Osmium(II) CNN Pincer Complexes as Efficient Catalysts for both Asymmetric Transfer and H2 Hydrogenation of Ketones / W., Baratta; M., Ballico; Chelucci, Giorgio Adolfo; K., Siega; P., Rigo. - In: ANGEWANDTE CHEMIE. INTERNATIONAL EDITION. - ISSN 1433-7851. - 47:(2008), pp. 4362-4365. [10.1002/anie.200800339]
Osmium(II) CNN Pincer Complexes as Efficient Catalysts for both Asymmetric Transfer and H2 Hydrogenation of Ketones
CHELUCCI, Giorgio Adolfo;
2008-01-01
Abstract
we have described the isolation of the first CNN pincer osmium complexes [OsX(CNN)P2] to display high catalytic activity and productivity in the reduction of ketones by either TH or HY (TOFand TON up to 106 h1 and 105, respectively). A high enantioselectivity (up to 98% ee) is possible in both reactions with a remarkably low catalyst loading (0.005–0.002 mol%). To the best of our knowledge, this is the first example of an osmium complex that catalyzes the asymmetric HY of ketones. Evidence for an Os-OR vs. Os-H equilibrium suggests that both these species are involved in the catalytic pathways.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.