Synthesis of the 3,3′-bipyrrole scaffold from diyne

Abstract

3,3′-Bipyrrole units often occur in biologically significant and materials-relevant compounds. However, the current efficient routes to afford these compounds are underdeveloped. Herein, a two-step approach for assembling substituted bipyrroles starting from 1,3-diyne and N-benzyl azomethine ylide has been demonstrated. In the first step, tungsten catalyzed twofold 1,3-dipolar cycloaddition gave rise to tetrahydrobipyrrole products in 42–85% yields. In the second step, a range of tetrahydrobipyrroles smoothly underwent copper-catalyzed dehydrogenative aromatization and provided 3,3′-bipyrroles in 54–80% yields. In addition, synthetic utilization and preliminary mechanistic studies were also performed. These bipyrroles might have potential utility in drug discovery and materials science.