Screening of ligands in the asymmetric metallocenethiolatocopper(I)-catalyzed allylic substitution with Grignard reagents

P-Chiral Monophosphorus Ligands for Asymmetric Copper-Catalyzed Allylic Alkylation

“…In 1995, Bäckvall and co-workers reported the first Cu-catalyzed asymmetric allylic alkylation between allylic chlorides and alkyl Grignard reagents with moderate enantioselectivity­(up to 42% ee) by employing a chiral arenethiolatocopper­(I) catalyst (Scheme , equation a) . The enantioselectivity was improved to 64% ee when a chiral ferrocenyl thiolate ligand was employed .…”

Multiple Acetylation of Pentaphenylferrocene – Synthesis and Asymmetric Reduction of 1‐Acetyl‐1′,2′,3′,4′,5′‐penta(para‐acetylphenyl)ferrocene

“…The reduction of 3 to alcohol ( R )‐ 16 in 98 % ee with ( S )‐CBS as catalyst (30 mol‐%) has been described, a reaction we repeated to give alcohol ( R )‐ 16 in 63 % yield. We recently reported the use of this same procedure for the asymmetric synthesis of the tetraphenylcyclobutadiene cobalt analogue ( R )‐ 17 .…”

A Comparison of Phosphaferrocene and Phospharuthenocene Ligands in Rh+‐Catalysed Enamide Hydrogenation Reactions: Superior Performance of the Phospharuthenocene

“…A probable explanation [8,9] lies in the observation that substituting Fe by Ru causes little electronic change if both coordinating functions are anchored to the same cyclopentadienyl ring, so that the dominant perturbations should reflect the longer Ru-centroid distance; because this relaxes the chiral architecture to confer better substrate access but diluted spatial organisation, the likely outcome (increased rate but lowered ee) is usually undesirable. [10] Experimental studies of Josiphos-type ligands 1 in Pd-catalysed allylic substitution reactions and Rh-catalysed hydroboration reactions, [8] as well as substituted aminomethylmetallocenethiolates 2 in copper-catalysed allylic acetate substitution reactions, [11] support this reasoning strongly. Equally, Fus pioneering study of the effects of substituting Ru for Fe in chiral azaindenyl complexes 3 produced results broadly in agreement with this analysis, with only a single case showing slightly enhanced enantioselectivity with ruthenium.…”