An η²-Aryl−Metal Interaction Turns a Chiral Monodentate Phosphoramidite into a Chelating Ligand in (S_a,S_Ru,R_C,R_C)-[RuCl(η⁶-p-cymene) (O,O‘-(1,1‘-dinaphthyl-2,2‘-diyl)-N-(1-(1,2-η-1-naphthyl)ethyl)- N-(1-(1-naphthyl)ethyl)phosphoramidite-κP)]PF₆

Abstract

C )-3 catalyzes the asymmetric cyclopropanation of styrene and R-methylstyrene with ethyl diazoacetate, giving good enantioselectivities for the latter olefin (up to 86% and 87% ee for the cis-and the transcyclopropane, respectively) when formed in situ in the presence of an excess of 1 to suppress ligand dissociation.

Chloro(η6‐p‐cymene)(phosphoramidite)ruthenium(II), a 16‐Electron Fragment Stabilized by an η2‐Aryl–Metal Interaction, and Its Use in Asymmetric Cyclopropanation

“…The complex formed upon chloride abstraction from 2b shows an unexpected (h 2 -arene)-metal interaction [23]. In the present paper, besides a full account of the products of chloride abstraction from [RuCl 2 (h 6 -p-cymene)(P*)], we describe the products of the dissociation of p-cymene from 2a and 3a, in which the coordination of the dangling aryl moiety of the P* ligand is turned from h 2 to h 6 , as well as additional catalytic experiments.…”

Neutral p-cymene ruthenium complexes with P-stereogenic monophosphines. New catalytic precursors in enantioselective transfer hydrogenation and cyclopropanation

“…Following previous studies with Ru/phosphoramidite ligands [16,17,22] the performance of complexes C as precatalysts in cyclopropanation of styrene and a-methylstyrene by controlled decomposition of ethyl diazoacetate was explored (Scheme 5).…”

“…In contrast, monodentate ligands [11e13] are still infrequent in stereoselective ruthenium catalysis. In this work we explore the potential of simple [RuCl 2 (p-cymene)(P*)] complexes in enantioselective hydrogen transfer and cyclopropanation, using a set of monodentate P-stereogenic ligands, previously described to be active in both Pd-catalysed hydrovinylation [14] and allylic alkylation [15] and less prone to secondary interactions such as those found in supposedly monodentate phosphoramidites [16,17].…”

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

“…[380,381] Ein Ruthenium-Phosphoramidit-Komplex katalysierte die Cyclopropanierung von Styrol und a-Methylstyrol mit Ethyldiazoacetat zu substituierten Cyclopropancarbonsäuren. Allerdings waren die Ausbeuten und Enantioselektivitäten meist niedrig, und die cis/trans-Verhältnisse betrugen bestenfalls 61:39.…”