Cyclisation of bisphosphonate substituted enynes

A new synthetic route to the bisphosphonate enyne tetraethyl hept-1-yn-6-en-4,4-diylbisphosphonate has been developed and the enyne has been used successfully in a range of transition metal-catalysed cyclisations that give structurally varied products. The motifs generated via such reactions provide new scaffolds for constructing bisphosphonic acids, an important class of therapeutic agents. NMR experiments indicate that the introduction of phosphonate substitutents onto cyclisation substrates provides a promising new approach to studying metal-catalysed cyclisations.

Graphical abstractDownload full-size imageA biphosphonate enyne undergoes a range of transition metal-catalysed cyclisations that give structurally varied products; monitoring the cyclisations by 31P NMR spectroscopy led to the observation of reaction intermediates.