Palladium-Catalyzed Asymmetric Hydrophosphination of Internal Alkynes: Highly Regio- and Stereoselective Construction of Axially Chiral Phosphines

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.

Nickel-catalyzed asymmetric synthesis of P-stereogenic vinyl phosphines

Addition reaction to alkynes is an efficient strategy for constructing valuable alkenyl compounds. However, the elusive regioselectivity has been a persistent challenge. In the context of hydrophosphination reaction which could afford valuable P-stereogenic phosphines, the control of enantioselectivity as well as regioselectivity were especially tricky. Here, we highlighted our recent work on the nickel catalyzed regio- and enantioselective hydrophosphination of unactivated alkynes with in situ generated secondary phosphines.

A Commercially Available Ruthenium Compound for Catalytic Hydrophosphination

Hydrophosphination with a commercially available ruthenium compound, bis(cyclopentadienylruthenium dicarbonyl) dimer ([CpRu(CO)2]2), was explored. Styrene derivatives or Michael acceptors react readily with either primary or secondary phosphines in the presence of 0.1 mol% of [CpRu(CO)2]2 under photolysis with an inexpensive and commercially available UV-A 9W lamp. In comparison to related photoactivated hydrophosphination reactions with [CpFe(CO)2]2 as a catalyst, these ruthenium-catalyzed reactions proceed at greater relative rates with lower catalyst loadings. <br>

A Commercially Available Ruthenium Compound for Catalytic Hydrophosphination

Hydrophosphination with a commercially available ruthenium compound, bis(cyclopentadienylruthenium dicarbonyl) dimer ([CpRu(CO)2]2), was explored. Styrene derivatives or Michael acceptors react readily with either primary or secondary phosphines in the presence of 0.1 mol% of [CpRu(CO)2]2 under photolysis with an inexpensive and commercially available UV-A 9W lamp. In comparison to related photoactivated hydrophosphination reactions with [CpFe(CO)2]2 as a catalyst, these ruthenium-catalyzed reactions proceed at greater relative rates with lower catalyst loadings. <br>

Room Temperature Ni(II) Catalyzed Hydrophosphination and Cyclotrimerization of Alkynes

The catalytic activity of nickel complexes in hydrophosphination involving secondary phosphines is not a commonly studied transformation. Beyond a small number of stand-out examples, many reports in the literature focus on the use of simple nickel salts. β-Diketiminates have been proven to be incredibly effective ligands for catalysis using a range of metal centers. This synthetic study investigates the catalytic ability of a Ni(II) β-diketiminate complex in the hydrophosphination of alkenes and alkynes, with a serendipitous discovery of its ability to effect alkyne cyclotrimerization and phosphine dehydrocoupling.