Palladium Catalyzed Asymmetric Hydrophosphination of Internal Alkynes: Access to Phosphine-Functionalized Axially Chiral Olefins

Asymmetric hydrophsophination of -bonds is a particularly important process in that the chiral phosphine products play a significant role as chiral ligands or catalysts. In contrast to the well-investigated asymmetric hydrophoshination of olefins and terminal alkynes that delivers central chirality, synthesis of the large family of axially chiral phosphines remains untouched via catalytic P-H functionalization. We now report a highly atroposelective Pd-catalyzed hydrophosphination of sterically hindered internal alkynes in regio- and E-specificity, where axially chirality and hydrophosphination are integrated. Both symmetrical and nonsymmetrical secondary phosphines are applicable. In the latter case, additional P-central chirality has been constructed. The resulting axially chiral phosphine are important precursors for further elaborations. This chemistry provides a new avenue to access underexplored chiral open-chain olefins and may provide new insight into atroposelective transformations of alkynes.