Synthesis of New Chiral Aryl Diphosphite Ligands Derived from Pyranoside Backbone of Monosacharides and Their Application in Copper‐Catalyzed Asymmetric Conjugate Addition of Diethylzinc to Cyclic Enones

Abstract

New chiral aryl diphosphite ligands based on the pyranoside backbones of glucose and galactose were prepared. These ligands were tested in the Cucatalyzed asymmetric conjugate addition of diethylzinc to cyclic enones with up to 88% ee. The stereoselectivity was found to be dependent on the ring size of the substrate as well as the ligand and copper source. The enantioselectivity depends on the absolute configuration of the C-4 stereogenic center of the ligand backbone, while the sense of enantioselectivity is mainly controlled by the configuration of the binaphthyl phosphite moieties.

A [5]HELOL Analogue That Senses Remote Chirality in Alcohols, Phenols, Amines, and Carboxylic Acids

“…Analyses of ( M , M )- 2 are illustrative. The 31 P NMRs of the phosphonamides 5 formed when ( M , M )- 2 is combined with ( S )- or ( R )- 10a are comprised of singlets at 151.09 and 150.86 ppm, respectively, relative to external 85% H 3 PO 4 , the region of the spectrum where phosphite resonances typically appear . When ( M , M )- 2 was combined with (±)- 10a , both of these singlets were seen, and the ratio of their intensities was 0.998 ± 0.02 .…”