CuH in a Bottle: A Convenient Reagent for Asymmetric Hydrosilylations

Significance

This group has shown that CuH complexed with the Takasago ligand is an excellent reagent for asymmetric hydrosilylation of various α,β-unsaturated carbonyl compounds. This paper describes a nice, stable ‘CuH in a bottle’ that provides retention of high enantioselectivities for long storage times (up to two months) of a 1 mM toluene solution of this reagent. The copper source for the CuH species showed different reactivity depending on the counter anion. This catalyst also proved to be robust enough for a microwave reaction showing high conversion and enantioselectivity. The presence of Ph₃P was shown to reduce the ee and ¹H NMR spectroscopy revealed a catalyst (1) hydride peak at 2.55 ppm that differs from the achiral Ph₃P-coordinated complex showing a hydride peak at 3.52 ppm.