Copper hydride (CuH), when complexed by the Takasago ligand (R)-(À)-DTBM-segphos, (1), [1] as shown in Scheme 1, is a remarkably reactive yet selective reagent for effecting asymmetric hydrosilylations. Aromatic ketones, [2a] hindered cyclic enones, [2b] aryl imines, [2c] and selected a,b-unsaturated esters and lactones [2d] all react with [{(R)-(À)-DTBM-segphos}CuH] (2) in the presence of stoichiometric PMHS [3] to afford the corresponding products of asymmetric reduction with excellent ee values. Substrate-to-catalyst (S/C) ratios typical of asymmetric hydrosilylations (< 500:1) mediated by other metals (e.g., Rh, Ti, Ru)

A study involving the relatively rare combination of heterogeneous catalysis conducted under microwave conditions is presented. Carbon-carbon bond formation, including Negishi and Suzuki couplings, can be quickly effected with aryl chloride partners by using a base metal (nickel) adsorbed in the pores of activated charcoal. Aminations were also studied, along with cross-couplings of vinyl alanes with benzylic chlorides as a means to stereodefined allylated aromatics. Reaction times for all these processes are typically reduced from several hours to minutes in a microwave reactor.

Asymmetric copper chemistry …︁ done heterogeneously? It's doable: Copper‐in‐charcoal (Cu/C) is introduced as an easily prepared catalyst that is readily converted in situ into a nonracemically ligated form of copper hydride that effects asymmetric hydrosilylations. DTBM=3,5‐di‐tert‐butyl‐4‐methoxydiphenylphosphinyl.

[reaction: see text] Exposure of any of several mono- or bidentate phosphines to CuCl leads to quick removal of unwanted ligands from solution. Most phosphines, if desired, can be easily recovered.

Copper hydride (CuH), when complexed by the Takasago ligand (R)-(À)-DTBM-segphos, (1), [1] as shown in Scheme 1, is a remarkably reactive yet selective reagent for effecting asymmetric hydrosilylations. Aromatic ketones, [2a] hindered cyclic enones, [2b] aryl imines, [2c] and selected a,b-unsaturated esters and lactones [2d] all react with [{(R)-(À)-DTBM-segphos}CuH] (2) in the presence of stoichiometric PMHS [3] to afford the corresponding products of asymmetric reduction with excellent ee values. Substrate-to-catalyst (S/C) ratios typical of asymmetric hydrosilylations (< 500:1) mediated by other metals (e.g., Rh, Ti, Ru)