Asymmetric Iron‐Catalyzed Hydrosilane Reduction of Ketones: Effect of Zinc Metal upon the Absolute Configuration

Solid-state proton NMR of paramagnetic metal complexes: DANTE spin echoes for selective excitation in inhomogeneously broadened lines

“…Chiral derivatives of this complex were successfully employed in hydrosilylation reactions of aromatic ketones [20][21][22]. We show that by using a large number of rotor periods K, the width of the rf spikelets can be made so narrow that one can tune the selectivity of the DANTE scheme to monitor barely resolved and partly overlapping signals stemming from inhomogeneous environments.…”

Asymmetric Hydrosilane Reduction of Ketones Catalyzed by an Iridium Complex Bearing a Hydroxyamide‐Functionalized NHC Ligand

“…Despite the enormous progress in the field of catalytic asymmetric synthesis, the development of asymmetric methods that lead to both enantioenriched products by using a single chiral source remains a significant challenge. [1,2] This concept of asymmetric catalysis provides a highly attractive synthetic tool using readily available single natural organic compounds such as amino acids.…”

“…However, the 1 H and 13 C NMR spectra showed very complicated sets of signals that were difficult to assign accurately. [13] In contrast to the iridium complex, a fully assignable NMR spectrum was obtained for complex 7, 2 by the same procedure as described for the synthesis of 4 and 6 ( Figure 1). The observation of the complicated sets of signals of…”

“…Catalytic asymmetric hydrosilylation was examined using acetophenone (1) and (EtO) 2 MeSiH in the presence of 4 (4 mol%) in THF at room temperature. After the reaction, a small amount of K 2 CO 3 in CH 3 OH was added to give (S)-1-phenylethanol (2). Representative results are summarized in Table 1.…”

Nickel(II)‐Dipyridylphosphine‐Catalyzed Enantioselective Hydrosilylation of Ketones in Air

“…[1] The non-noble-metal-catalyzed enantioselective hydrosilylation of prochiral ketones represents a rewarding transformation towards chiral alcohols owing to the economic benefits and the operational simplicity of such methods. [2] Thus, in the past two decades, a variety of effective chiral transition-metal catalysts based on titanium, [3] zinc, [4] tin, [5] copper, [6,7] iron, [8,9] and cobalt [10] have been accordingly developed and applied in the asymmetric hydrosilylation of ketones with good to excellent enantioselectivities. Nickel-based catalysts have shown better activities in heterogeneous and some homogeneous reactions, such as hydrogenation and cross-coupling reactions, than other catalytic systems mediated by biologically relevant metals, for example, Fe, Cu, or Zn.…”