Dehydroxylative Noncanonical C–C Bond Arylation of Cyclopropanols: The Origin of Distal Selectivity via Remote Steric Effects

Precise activation of otherwise inert
σ-bonds such as C(sp3)–C(sp3) and
C(sp3)–OH
remains a formidable challenge in homogeneous catalysis. While recent
advances have harnessed cyclopropyl alcohol as a masked homoenolate
or employed directing-group-assisted C–C bond insertion, these
strategies exclusively follow conventional β-scission pathways.
Herein, we report a noncanonical deoxygenative γ-C–C
bond activation of cyclopropyl alcohols, enabling cross-coupling without
the formation of homoenolate. Key to the transformation is tris(3,5-di-tert-butylphenyl)phosphine that creates a tris-ligated,
pentacoordinate nickel transition state. The large cone angle directs
oxidative addition to the distal C–C bond, while a low buried
volume (% Vbur) preserves coordination
sites. Competing homoenolate chemistry through β-scission is
effectively suppressed by boronate masking under biphasic conditions.
A series of mechanistic studies support a rate-determining γ-oxidative
addition via a pentacoordinate transition state. The resulting π-allyl
nickel intermediate undergoes intramolecular transmetalation in a
highly regioselective C–C bond-forming event, forging a wide
array of 1,1-dialkylethenes. This work establishes a distinct mechanistic
framework for C–C bond activation, expanding the synthetic
utility of cyclopropanol-based cross-coupling.