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%).