Mesoionic Carbene‐Catalyzed Synthesis of 1,2‐Dialkoxyethenes and 1,4‐Dioxepines From Aromatic Aldehydes and Alkyl Tosylates

1,2‐Dialkoxyethenes are crucial building blocks in organic synthesis, medicinal chemistry, and materials science. However, their practical preparation remains limited by harsh reaction conditions, poor regioselectivity, or reliance on toxic transition metals. Herein, we report a transition‐metal‐free, Mesoionic Carbene (MIC)‐catalyzed protocol for the efficient synthesis of diverse acyclic 1,2‐dialkoxyethenes with exclusive E ‐selectivity and 1,4‐dioxepines from readily available aryl aldehydes and alkyl tosylates. The reaction proceeds through an in situ benzoin condensation followed by sequential O ‐alkylation under mild conditions, affording the target products in up to 90% yield with broad functional group tolerance. This operationally simple, metal‐free strategy provides a sustainable and practical alternative to existing transition‐metal‐dependent approaches for valuable 1,2‐dialkoxyethene frameworks.