Azirine-Based Synthesis of Alkynylpyrroles.

A two-step method for the preparation of β-ethynylpyrroles from azirinyl ethynyl ketones by Wittig olefination, followed by FeCl2-catalyzed isomerization, has been developed. Azirines with various substitution patterns of the ring and the triple bond tolerate the reaction conditions of both steps, providing di-, tri-, and tetra-C-substituted β-ethynylpyrroles from fair-to-good yields.