ChemInform Abstract: Modular, Concise, and Efficient Synthesis of Highly Functionalized 5‐Fluoropyridazines by a [2 + 1]/[3 + 2]‐Cycloaddition Sequence.

Abstract The [2+1] reaction of terminal alkynes [e.g. (I)] and difluorocarbene ([II] or [IX]) gives difluorocyclopropenes [e.g. (III)] which further go through [3 + 2]‐cycloaddition with diazo compounds [e.g. (IV)] to furnish fluoropyridazines [e.g. (VI)].