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Updated: Sep 18, 2026

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
Published on: August 16, 2018
Ring-Retentive Allylation of Cyclopropanols Through Interception of Enolized Homoenolates by π-Allylpalladium
Kento Tsukiji1, Sena Miura1, Naohiko Yoshikai1
1Graduate School of Pharmaceutical Sciences, Tohoku University, Sendai, Japan.
Abstract:
Enolized homoenolates have emerged as distinct intermediates in cyclopropanol chemistry, enabling bond constructions beyond classical homoenolate and β-keto radical manifolds. Their reactions with intrinsically electrophilic partners are established, but interception by catalytically generated electrophiles has remained unexplored. Herein, we report a palladium-catalyzed, zinc-mediated formal "allylic cyclopropylation" of cyclopropanols with allyl acetates. The reaction installs diverse allyl groups through transient ring opening to an enolized homoenolate, interception by π-allylpalladium, and ring closure, thereby preserving the cyclopropane framework. An enantioselective variant, particularly effective for bicyclic substrates, demonstrates stereochemical control over these transient intermediates. Stereochemical experiments support a double-inversion pathway characteristic of Tsuji-Trost reactivity. These findings integrate enolized homoenolates with transition-metal catalysis and expand the scope of ring-retentive cyclopropanol functionalization.
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