Organic base-promoted formal [4+1] cycloaddition of vinylethylene carbonates with elemental sulfur for facile access to thiophenones.

Thiophenones are traditionally prepared from pre-functionalized sulfur substrates in the presence of metal catalysts, oxidants, and strong acids and bases, which represent harsh reaction conditions and result in low efficiency. Herein, an organic base-promoted 2(5H)-thiophenone construction with cheap and easily available vinylethylene carbonates and elemental sulfur through a novel [4+1] cyclization process is disclosed under mild reaction conditions.