Chiral Spiro‐Scaffolded C(sp ³ ),P‐Chelated Iridacycles: Direct Asymmetric Hydrogenation of β,β‐Disubstituted Acrylate Salts

ABSTRACT

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, sp ³ ‐hybridized carbanion ligands have long been underexplored owing to the inherent instability of C(sp ³ )‐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(sp ³ ),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(sp ³ )‐metalated complex‐based catalysis, opens new avenues for the development of innovative asymmetric catalytic systems, and unlocks access to previously inaccessible enantioselective transformations.