Hydrofunctionalizations of Allenes and Alkynes

In course of the past 8 years, we have developed a wide range of rhodium-catalyzed, branched-selective allylation reactions starting from either alkynes or the isomeric allenes, both terminal and internal. By choosing a suitable ligand for the catalytic system and applying appropriate reaction conditions, we were able to couple numerous pronucleophiles, allowing for C−O, C−S, C−N, and C−C bond formation. Many of these methodologies display additional degrees of selectivity. Particularly, many methods have been reported asymmetrically or show a high degree of regioselectivity when more than one nucleophilic functionality is present. So far, this development has led to significant advances in the field of transition metal-catalyzed allylation reactions, which had previously only been known to a limited degree. Nowadays, the growing maturity of this particular field of research makes hydro- functionalizations of alkynes and allenes a worthy, atom-economic alternative to previously established methods such as allylic substitution or oxidation reactions. This was also shown by several applications in target-oriented synthesis. Nevertheless, a large potential has not been touched so far, with many more pronucleophiles, internal alkyne and allene substrates and applications in total synthesis possible. For recent reviews, see: