Pseudo enantiomeric mixed s/p ligands derived from carbohydrates for the 1,4-addition of phenyl boronic acid to cyclohexenone

Abstract

The application of phosphinite-thioglycosides and phosphine-thioglycosides ligands in the Rh(I)-catalyzed 1,4-addition of phenylboronic acid to cyclohexenone is reported. Among the ligands tested, phosphinite-thioglycoside 3 and phosphine-thioglycoside 10, bearing a 1,2-cis arrangement of the two heteroatoms, have exhibited the best results in terms of reactivity and enantioselectivity. Interestingly, ligands 3 and 10, both derived from D-sugar are able to generate the addition product of the phenylboronic acid to the cyclohexenone with opposite configuration, behaving thus as enantiomers