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.