1-Phospha-Butadienes and 1H-Phospholes via Alkynylation of Acetylenic Phosphaalkenes

Carbon-rich motifs are important building blocks for the fabrication of functional and opto-electronic materials. Electronic tuning can be achieved by alteration of bonding topologies but also via incorporation of heteroelements, for example phosphorus. Herein we present the palladium/copper mediated formation of branched 1-phospha-butadiene derivatives through an unusual alkynylation of a phospha-enyne fragment. Structural and NMR studies provide mechanistic insights into this alkynylation. Furthermore, we disclose a complex cyclisation of the thus obtained 3-yne-1-phosphabutadiene motifs to give highly substituted phosphole derivatives identified by 2D NMR and SC-XRD analysis.