The synthesis and reactions of novel butadiyne derivatives

The synthesis, isolation and characterisation of aryl and heteroarylbutadiynes is herein reported. X-ray structural analysis for terminal butadiynes 72,118, 143, 157, 162 and 172 has been obtained. The packing diagrams indicate, in most cases, a hydrogen bonding interaction between the terminal acetylenie proton and the appropriate atom in the ring. An important feature of our synthetic methodology is the use of the 2-hydroxy-2-propyl protecting group, which facilitates purification from protected species, due to a large difference in polarity. The synthesis of mono- and di-deprotected bis-butadiynes is also reported; indeed X- ray structural analysis of di-deprotected pyridyl bis-butadiyne 234 has been obtained, as shown in the figure below The reactions of aryl and heteorarylbutadiynes and bis-butadiynes have also been investigated, leading to the synthesis of molecular-wire precursors 262 and 264.