Main group and transition metal-mediated phosphaalkyne oligomerizations

The first isolable phosphaalkyne was discovered by Becker, Gresser, and Uhl in 1981. Since this initial discovery, the chemistry of phosphaalkynes has continuously attracted attention. Several routes for the preparation of phosphaalkynes have been described and they exist with a wide variety of substituents. Phosphaalkynes are versatile ligands to transition metals, displaying a wide range of coordination modes. Under properly chosen conditions, phosphaalkynes readily undergo oligomerizations. Uncontrolled thermal reactions give rise to mixtures of cage compounds, whereas metal-mediated phosphaalkyne oligomerizations allow increased control, leading selectively to products such as dimers A- C, trimers D- E, tetramers F- I or higher oligomers J- K. This review describes each type of phosphaalkyne oligomerization and focuses on the reactions mediated by main group and transition metals.