Hydrosulfonylation of Alkynes for Stereodivergent Synthesis of Vinyl Sulfones: Synthetic Strategy and Mechanistic Insights

Abstract

Direct synthesis of thermodynamically less favorable ( Z )-vinyl sulfones presents a notable challenge in organic synthesis. In addition, the development of a stereodivergent synthesis for ( E )- and ( Z )-vinyl sulfones is crucial but remains elusive. In this study, we present a hydrosulfonylation of aryl-substituted alkynes, achieving a stereodivergent synthesis of ( E )- and ( Z )-vinyl sulfones by leveraging both thermodynamic and kinetic controls. Notably, the synthesis of challenging ( Z )-vinyl sulfones was achieved through a kinetically controlled process without the need for a catalyst. To synthesize ( E )-vinyl sulfones, unconventional visible light-mediated isomerization was employed as a means of facilitating the transition to the thermodynamically favored form. The present study encompasses a comprehensive experimental and computational investigation, which provides valuable insights into the reaction mechanism. This investigation reveals two plausible isomerization pathways: a novel double spin-flip mechanism and a hydrogen atom transfer process in the presence of eosin Y. This study not only advances our understanding of isomerization mechanisms beyond conventional energy-transfer routes but also offers a robust and switchable strategy for synthesizing ( E )- and ( Z )-vinyl sulfones, thereby providing a versatile avenue for the creation of valuable compounds in the fields of organic synthesis and medicinal chemistry.

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