Rhodium‐Catalyzed Asymmetric Aqueous Pauson–Khand‐Type Reaction

Abstract

An interesting rhodium-catalyzed asymmetric aqueous Pauson-Khand-type reaction was developed. A chiral atropisomeric dipyridyldiphosphane ligand was found to be highly effective in this system. This operationally simple protocol allows both catalyst and reactants to be handled under air without precautions. Various enynes were transformed to the corresponding bicyclic cyclopentenones in good yield and enantiomeric excess (up to 95 % ee). A study of the electronic effects of the enyne substrates revealed a correlation between the electronic properties of the substrates and the ee value obtained in the product of the Pauson-Khand-type reaction. A linear free-energy relationship was observed from a Hammett study.

Transition metals in organic synthesis: Highlights for the year 2005

“…Asymmetric cobalt-catalyzed intermolecular Pauson-Khand reactions were reported [997]. An asymmetric intermolecular Pauson-Khand reaction of cobalt-alkyne complexes having a chiral bridging ligand [998] and a rhodium-catalyzed asymmetric Pauson-Khand reaction in water [999] was described. Rhodium catalyzed an allylic alkylation-Pauson-Khand sequence [1000].…”

Palladium–(S,pR)‐FerroNPS‐Catalyzed Asymmetric Allylic Etherification: Electronic Effect of Nonconjugated Substituents on Benzylic Alcohols on Enantioselectivity

“…It is complementary to the well-known electronic effect on stereoselectivity of either a substrate or a ligand composed of conjugated aromatic systems. [16] To further extend the scope of the reaction with respect to the alcohol substrate, ortho-and meta-substituted benzylic alcohols (Table 3, entries 1-3) were applied successfully in the AAE to give the ether products in high yield with high enantioselectivity. The Pd-L5 catalytic system was also found to be compatible with heterocycles (Table 3, entries 5-8).…”

P-Phos: A Family of Versatile and Effective Atropisomeric Dipyridylphosphine Ligands in Asymmetric Catalysis

“…Interestingly, this protocol allowed the handling of both the catalyst and the reactants under air without special precautions. 44 The higher concentration of reactants in conventional organic solvents proved to offer higher rates in the PKR. This significant finding prompted us to use water as the sole solvent, which was expected to increase the effective concentration of the reactants according to the aqueous micellar concept 45 and thereby to accelerate the reaction.…”