Regioselective Reversal Cyclization To Access either Eight-Membered Sulfur-Containing Heterocycle-Fused γ‑Pyrones or 2‑(1,4-Dithianyl)-4-pyrones from the Same Precursors

A regioselective
reverse strategy for the construction of eight-membered
sulfur-containing heterocycle-fused γ-pyrones and 2-(1,4-dithianyl)-4-pyrones
starting from 2-diazo-γ-pyrones and dithioacetals was achieved
for the first time. The process combines C–S bond formation
via sulfur ylides and C–C bond formation via electron transfer
to afford the target molecules in a facile manner with 100% regioselectivity
and in excellent isolated yields (up to 90%).