Annulative Coupling of Sulfoxonium Ylides with Aldehydes and Naphthols or Coumarins: Easy Access to Fused Dihydrofurans.

We present a novel, metal- and additive-free method for the robust synthesis of dihydrofuran-fused naphthalenes and coumarins. This approach utilizes the annulative coupling of sulfoxonium ylides with aldehydes, naphthols, or coumarins at ambient temperature. The method exhibits broad substrate compatibility, accommodating various functional groups on sulfoxonium ylides and naphthol or coumarin derivatives and resulting in good to high yields of the desired products. Additionally, we successfully scaled up the reactions, and the synthesized derivatives were further converted to other valuable bioactive molecules, validating the viability of our approach.