A Convenient Iodine‐Promoted Synthesis of α‐Ketothioesters

Abstract

An effective and practical synthesis of α‐ketothioesters has been reported for direct oxidative thioesterification of substitutional acetophenones with dimethyl sulfoxide and iodine in the presence of boric acid and acetic anhydride in high yields. According to the control experiments and literatures, the reaction mechanism was proposed to undergo via Pummerer rearrangement.

Iodine and DMSO as Surrogate of Hazardous Metal and Non‐Metal Reagents in Organic Synthesis

“…However, the traditional synthetic routes to these moieties involve the use of toxic catalysts such as pyrrolidine (Scheme 56 (a)), [555] PPh 3 supported by HBr (Scheme 56 (b)), [556] and TBAI supported by K 2 S 2 O 8 (Scheme 56 (c)), [557] which limit their substrate scope. To overcome these limitations, Zhao and colleagues have developed a new synthetic route using acetophenone derivatives as precursors for the synthesis of thioesters (Scheme 56 (d)) [558] . The standard conditions for this process involve the use of 0.5 equivalents of iodine and 1.0 equivalent of boric acid dissolved in 1.0 mL of Ac 2 O, followed by the addition of 2.5 mL of DMSO and stirring at 80 °C.…”

“…To overcome these limitations, Zhao and colleagues have developed a new synthetic route using acetophenone derivatives as precursors for the synthesis of thioesters (Scheme 56 (d)). [558] The standard conditions for this process involve the use of 0.5 equivalents of iodine and 1.0 equivalent of boric acid dissolved in 1.0 mL of Ac 2 O, followed by the addition of 2.5 mL of DMSO and stirring at 80 °C. The role of DMSO in this reaction is to act as a source of À SMe, and the reaction cannot proceed without the presence of boric acid highlighting the pivotal roles of boric acid.…”