CuH in a Bottle: A Convenient Reagent for Asymmetric Hydrosilylations

Abstract

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)

Application of a C2-Symmetric Copper Carbenoid in the Enantioselective Hydrosilylation of Dialkyl and Aryl–Alkyl Ketones

“…4 In particular, stabilized copper hydride species are powerful reducing agents for numerous reductive transformations, among them hydrosilylation of ketones. 5 Tertiary phosphines are widely employed as ligands for hydrosilylation catalysts, particularly chiral ones, owing to their highly tunable steric and electronic properties. Comparable in their attributes but much less extensively employed are N-heterocyclic carbene (NHC) ligands.…”

Rediscovering Organocopper Chemistry Through Copper Hydride. It’s All About the Ligand

“…Indeed, he found a prescription for DTBM-SEGPHOS-complexed copper hydride using copper(II) acetate monohydrate 31 (rather than in situ generated t-BuOCu, from CuCl + t-BuONa) 3,22 that could be conveniently stored in a bottle 'on the shelf' for months ( Figure 9). 32 All that needs to be done to make enough for 50 one-millimole-scale reactions is to put hardly anything worth anything (other than the ligand) in a brown bottle: 10 mg of Cu(OAc) 2 ·H 2 O, 44 mL of anhydrous toluene, 6 mL of Lancaster's PMHS, and only 59 mg of DTBM-SEGPHOS (Scheme 11). The resulting solution allows for a conservative 1000:1 substrate/ligand ratio with a one-milliliter aliquot for a reaction involving one millimole of substrate.…”

Avanços recentes na hidroaminação de compostos insaturados

“…Recentemente, Hartwig e colaboradores reportaram o uso de Cu(PPh 3 )H catalítico, ligante (S)-DTBM-SEGPHOS (DTBM = 3,5-di-terc-butil-4-metoxi), 50 HSiMe(EtO) 2 e uma fonte eletrofílica de grupo amino (Bn 2 N-OBz) para realizar hidroaminação de olefinas 1,2-dissubstituídas com a posição homoalílica funcionalizada. 51 Esses resultados fornecem uma rota simples para acessar fragmentos 1,3-aminoálcoois.…”