Palladium-catalyzed unprecedented atroposelective hydrophosphination of internal alkynes has been realized using diarylphosphines, affording C-N axially chiral trisubstituted olefins (vinylphosphines) in excellent regioselectiviry, (E)-selectivity, and enantioselectivity. The axial chirality was established via integration of hydrophosphination and dynamic kinetic transformation of the alkynes, with both symmetrical and nonsymmetrical secondary phosphines being applicable. In the latter case, additional P-central chirality has been constructed in good diastereoselectivity.
<div>A highly chemo- and regioselective cyclo(co)trimerization between 3-halopropiolamides and symmetrical internal alkynes is reported. The reaction is catalyzed by Ru(II)-complexes and proceeds at ambient temperature in ethanol to deliver fully substituted dihalogenated isophthalamides. 1,4-Butynediol was found to undergo spontaneous lactonization with halopropiolamides after trimerization to provide 5,7-dihalo-phthalide products.</div>
AbstractOrganophosphines are an important class of ligands widely used in organic chemistry. Although great progress has recently been made in the rapid construction of new phosphines through Rh- or Ru-catalyzed C–H bond functionalizations, synthetic access to more diverse phosphines remains a challenge. We describe an efficient process for the rhodium-catalyzed phosphorus(III)-directed hydroarylation of internal alkynes to generate various alkenylated and 2′,6′-dialkenylated biarylphosphines with high selectivity. A range of diverse alkynes and phosphines were effectively prepared with broad functional-group compatibility under the optimized conditions. In addition, the developed protocol can be extended to modify chiral phosphine ligands, providing enantioenriched alkenylated phosphines without erosion of the enantiomeric excess.
Palladium-Catalyzed Asymmetric Hydrophosphination of Internal Alkynes: Highly Regio- and Stereoselective Construction of Axially Chiral Phosphines
