Water-catalytic deconstructive and proton transfer cyclopropanation of sulfoxonium ylide with olefin is developed through a sequential water-mediated ring-closing/opening reaction. This atom-economical, environmentally friendly methodology offers easy access to a range of cyclopropyl ketones with moderate to good yields.
Abstract
Cyclopropane rings, with their distinct structure and reactivity, have long been a focus in organic chemistry and are significant pharmacophores in medicinal chemistry. Conventional direct cyclopropanation methods for olefins do not modify the functional groups on the α– or β-carbon of olefins. Herein, a novel deconstructive cyclopropanation reaction is designed for olefins using a close–open–close ring strategy. This enables the migration of functional groups to the α– or β-carbon of olefins, leading to the formation of regioselective cyclopropane compounds, which is a previously unreported approach. By exploiting the zwitterionic property of sulfoxonium ylides and combining them with Density Functional Theory (DFT) computations, the reaction is proposed to proceed via a [2 + 2] cycloaddition to form a strained cyclobutene intermediate, followed by cyclobutane ring-opening and nucleophilic substitution through a water-involved proton-shuttle process for ring closure. Hydrogen-bonding interactions play a significant role in controlling the regioselectivity.
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