Tunable Lewis Basicity and Nucleophilicity of Water against α,α-Dihalo-β-acetoxyketones for the Selective Synthesis of α-Haloenones and 1,2-Diketones

Abstract

The discovery and systematic study of tunable yet competitive nucleophilicity and Lewis basicity of water against novel building blocks α,α-dihalo-β-acetoxyketones (possessing a tertiary acetate) have been reported. This distinct reactivity resulted in the formation of two competitive and different products 1,2-diketones and α-haloenones from a common intermediate α,α-dihaloβ-acetoxyketones through the nucleophilicity and Lewis basicity of water, respectively. A systematic study to understand the effect of temperature and amount of water on the product distribution revealed that a lower temperature in combination with a higher amount of water shows a high preference for 1,2-diketones over α-haloenones. Measuring the dielectric constant (permittivity, ε) of various reaction media at various temperatures and a correlation with the experimental observations suggested that the reaction media with a higher dielectric constant exhibit the nucleophilic character and hence show a preference for 1,2-diketones over αhaloenones.

Cationic [1,5]‐Aryl Migrations of Propargyl Benzyl Ethers – A Stereospecific Approach to E‐ and Z‐Tetrasubstituted Olefins

“…Our research group has been actively involved in the development of unconventional synthetic transformations by employing propargylic derivatives like alcohols and acetates against electrophilic NXS (Nhalosuccinimide) reagents. [9] In continuation of our thirst for propargylic derivatives, we envisioned an opportunity to explore the reactivity of propargylbenzyl ethers [10] against NXS reagents.…”