Diastereoselective Umpolung cyclisation of ketones promoted by hypervalent iodine

Abstract

Umpolung reactivity facilitated by hypervalent iodine has emerged as an appealing method for the efficient α‑functionalisation of ketones. However, skeletal reorganisation or migration reactions remain comparatively underexplored, primarily due to the challenging taming of transient carbocationic intermediates. In this study, we introduce a method for the functionalisation of ketones, employing a 6-endo-trig cyclisation initiated by Umpolung of silyl enol ethers, resulting in the diastereoselective formation of syn-substituted cyclohexanes. Additional investigations, both experimental and computational, give insight into the mechanistic intricacies of this process, and shed light on an unconventional I(III)‑reactivation mechanism.