An Atropos Biphenyl Bisphosphine Ligand with 2,2′‐tert‐Butylmethylphosphino Groups for the Rhodium‐Catalyzed Asymmetric Hydrogenation of Enol Esters

Abstract

This is an update of our previous work concerning the development of Atropos biphenyl bisphosphine ligands. An unexpected Atropos structural property was confirmed by single crystal X-ray diffraction and this result is consistent with the computational calculations described in our previous work. This P-stereogenic bisphosphine ligand possessing a biphenyl backbone and 2,2'-tertbutylmethylphosphino groups has been applied to the Rh-catalyzed asymmetric hydrogenation of enol esters, which has not been widely studied and can be used for the synthesis of several important bioactive compounds. Although there is room for further improvement in enantioselectivity, the results reported herein provide a further understanding of such types of ligands.

Asymmetric Hydroacylation Involving Alkene Isomerization for the Construction of C3‐Chirogenic Center

“…Solvents and ligands play critically important roles in this reaction. Thed esired product 2a could only be obtained in 1,4-dioxane.A dditionally,o nly the bulky tBu substituted bisphosphine ligands,D TBM-SegPhos (L3)a nd BipheP* (L4), [10] could afford 2a (entries 1-4 and Table S1 in SI). The latter gave the desired product in 24 %yield (remainder being unreacted (E)-1a)a nd 64/36 er, while the former provided apromising result of 76 %yield (with the rest of the material being the decarbonylated byproduct 2a' ' [11] )a nd 98/2 er.…”

P-Stereogenic Phosphorus Ligands in Asymmetric Catalysis

“…Rhodium-catalyzed asymmetric hydrogenations of enol esters have been reported by several research groups. ,− Scheme shows the asymmetric hydrogenation of simple enol acetates using TangPhos as the chiral ligand . When ethyl acetate was used as an optimum solvent, high enantioselectivities of up to 99% ee were observed.…”

Gold(I) Complexes with Ferrocenylphosphino Sulfonate Ligands: Synthesis and Application in the Catalytic Addition of Carboxylic Acids to Internal Alkynes in Water

“…Enol esters represent an important class of synthons in organic chemistry, commonly employed as intermediates, among others, in cross-coupling [1][2][3], asymmetric hydrogenation [4][5][6], and cyclization reactions [7][8][9], as well as monomers in polymerization and oligomerization processes [10][11][12]. Among the different methods of synthesis of these valuable molecules, the intermolecular addition of carboxylic acids to alkynes catalyzed by transition metals (hydro-oxycarbonylation reaction) is probably the most straightforward and atom-economical one because the starting materials are widely available and no byproducts are generated in the process.…”