Allylic C–S Bond Construction through Metal-Free Direct Nitroalkene Sulfonation

Abstract

A metal-free, open-flask protocol was developed for the preparation of allylic sulfones through direct condensation of sodium arylsulfinates and β,β-disubstituted nitroalkenes. The key step of this process was the Lewis base-promoted equilibrium between nitroalkenes and allylic nitro compounds. Through this process, the readily available conjugated nitroalkenes can be easily converted into allylic nitro compounds, which contain more reactive C═C bonds toward the sulfonyl radical addition. As a result, allylic sulfones were prepared in excellent yields with a broad substrate scope under mild conditions.

Synthesis and applications of sodium sulfinates (RSO2Na): a powerful building block for the synthesis of organosulfur compounds

“…Lei et al reported a metal-free direct denitro-sulfonylation reaction between β,β-disubstituted nitroalkenes and sodium arylsulfinates to give allyl sulfones ( Scheme 122 ). 186 The iodine-catalyzed direct condensation of both reactants of β,β-disubstituted nitroalkenes and sodium arylsulfinates bearing electron-donating and electron-withdrawing groups was successfully explored in this protocol. An array of allyl sulfones was obtained in good to high yields with high selectivity.…”

Recent Progress in Sulfonylation via Radical Reaction with Sodium Sulfinates, Sulfinic Acids, Sulfonyl Chlorides or Sulfonyl Hydrazides

“…In 2018, the direct condensation of sodium arylsulfinates and β,β-disubstituted nitroalkenes for the preparation of allylic sulfones was realized by Chen group. [28] The Lewis basepromoted equilibrium between nitroalkenes and allylic nitro compounds was the key step for this reaction. The desired products can be isolated in a high selectivity and yield.…”

Denitrative Cross-Couplings of Nitrostyrenes

“…In the light of these three discoveries, Shi and Chen observed a very different reaction outcome when α-substituted nitrostyrenes 1 reacted with the sodium salt of aryl sulfinic acids 23 ( Scheme 20 ) [ 61 ]. Unlike in the previous reports, the reaction between sodium sulfinic acid salt and the nitroolefin yielded allylic sulfones instead of the conjugated sulfones.…”