Asymmetric Hydrosilylation of Prochiral Ketones Catalyzed by Nanocrystalline Copper(II) Oxide

Abstract

Asymmetric hydrosilylation of aryl alkyl ketones to afford chiral secondary alcohols with good yields and excellent enantioselectivity is realized by using nanocrystalline copper(II) oxide and BINAP in the presence of organosilanes as the stoichiometric reducing agents.

Asymmetric Zinc‐Catalyzed Hydrosilylation of Ketones and the Effect of Carboxylate on the Enantioselectivity

“…Chiral ammonium fluoride as catalyst had also been reported. The use of copper hydride in the hydrosilylation of aryl ketones with excellent results has been reported by Lipshutz; therefore, chiral tertiary phosphines are widely employed as ligands for copper catalysts . Similar to rhodium and iridium, C 2 ‐symmetric copper‐bound N ‐heterocyclic carbene exhibits extraordinary enantioselectivity in the catalytic hydrosilylation of ketones .…”

“…The use of copper hydride in the hydrosilylation of aryl ketones with excellent results has been reported by Lipshutz 18 ; therefore, chiral tertiary phosphines are widely employed as ligands for copper catalysts. [19][20][21][22][23][24] Similar to rhodium and iridium, C 2 -symmetric copper-bound N-heterocyclic carbene exhibits extraordinary enantioselectivity in the catalytic hydrosilylation of ketones. 25 More recently, the use of zinc species in hydrosilylation reactions became an interesting research field.…”

Convenient Enantioselective Hydrosilylation of Ketones Catalyzed by Zinc‐Macrocyclic Oligoamine Complexes

“…However, these reductions require expensive chiral diphosphine ligands, such as 3,5-xyl-MeO-BIPHEP, [18] BINAP [19,20] or DTBM-SEG-PHOS, [21] although in several cases the catalyst could be used at a very low load (S/C > 1000:1).…”

Recyclable Stereoselective Catalysts

“…The secondary alcohols can be obtained in very good yields and enantioselectivities after hydrolysis with tetrabutylammoniumfl uoride (TBAF) (up to 99% ee). This heterogeneous catalyst was reused three times without any yield or enantioselectivity erosion [33] .…”