Chiral Spiro-Scaffolded C(sp³),P-Chelated Iridacycles: Direct Asymmetric Hydrogenation of β,β-Disubstituted Acrylate...

Rational design of chiral ligands with precisely tailored steric and electronic properties is pivotal to advancing asymmetric transition-metal catalysis. Despite their promising strong σ-donating ability, sp³-hybridized carbanion ligands have long been underexplored owing to the inherent instability of C(sp³)-metalated complexes. In this study, we report a modular design of chiral spiro monophosphine ligands ((R)-SciPhos) integrating an electronic-withdrawing group, a quaternary carbon moiety, and a rigid spiro scaffold, which efficiently addresses this long-standing challenge. This judicious design enables the synthesis of bench-stable neutral C(sp³),P-chelated iridium complexes via intramolecular C─H activation. These novel iridacycle catalysts exhibit high efficiency, excellent enantioselectivity, and a broad substrate scope in the asymmetric hydrogenation of challenging β,β-disubstituted sodium acrylates, achieving up to 99% yield and 97% ee with a turnover number (TON) of 5000. Mechanistic studies reveal an Ir(III)/Ir(V) catalytic cycle involving an olefin dihydride iridium(III) intermediate, wherein the migratory insertion step dictates enantioselectivity via noncovalent interactions. This work establishes a general platform for C(sp³)-metalated complex-based catalysis, opens new avenues for the development of innovative asymmetric catalytic systems, and unlocks access to previously inaccessible enantioselective transformations.