Metal‐Free Regioselective 1,6‐Conjugate Addition of Sulfide to para‐Quinone Methides: Simple Access to E‐Selective Thiaoxacyclophanes

We realized a simple approach involving the 1,6‐conjugate addition (regioselective thiolation) of para‐quinone methides (p‐QMs) with easily available thio‐based nucleophiles. Through ring‐closing metathesis (RCM), this procedure delivered a variety of para‐ and meta‐thiaoxacyclophanes as E‐isomers in good yields. A simple thiol‐free one‐pot approach is reported for the direct synthesis of sulfides and sulfones under green reaction conditions without the use of any metal catalysts. Low‐cost and easily accessible compounds such as p‐QMs and benzyl bromides are used as starting materials in the presence of potassium thioacetate (PTA) and Oxone®. Novel thiaoxacyclophanes were assembled in three simple steps including conjugate addition of PTA, Grignard addition, and RCM sequence. We demonstrated a simple and useful method for assembling diaryl methyl thioethers by 1,6‐conjugate addition (regioselective thiolation) of PTA to p‐QM derivatives. The key aspects of this transformation include access to thiaoxacyclophanes. A simple thiol‐free one‐pot approach is reported for the direct synthesis of sulfides and sulfones under green reaction conditions without the use of any metal catalysts.