Nickel-Catalyzed H2-Enabled Asymmetric Olefin Isomerization: Direct Access to P-Stereogenic Phospholenes With Adjacent Stereocenters.

Asymmetric olefin isomerization capable of constructing consecutive or heteroatom stereocenters remains a long-standing challenge in asymmetric synthesis. Here, we report a nickel-catalyzed enantioselective isomerization of syn-substituted 2,5-dihydrophosphole 1-oxides. Under a hydrogen atmosphere, this reaction proceeds with high chemo- and stereoselectivity, affording 2,3-dihydrophosphole 1-oxides in up to 99% yield, >20:1 dr, and 98% ee, without detectable hydrogenation byproducts. This reaction enables the simultaneous construction of two contiguous stereocenters, including a P-stereogenic center. Mechanistic studies and DFT calculations indicate that a kinetically favored β-hydride elimination pathway, stabilized by electronic and noncovalent interactions, accounts for the excellent chemoselectivity. The resulting chiral phospholene oxides serve as versatile intermediates for the synthesis of valuable phospholanes and phosphine ligands, demonstrating their synthetic utility.