Direct nucleophilic substitutions of allylic alcohols with 1,3-dicarbonyl compounds: Synthetic design, mechanistic aspects and applications

The nucleophilic allylic substitutions have become one of the most powerful tools for the construction of carbon-carbon and carbon-heteroatom bonds in organic chemistry. This review focuses on the main previous reports dealing with the evolution of the direct nucleophilic substitutions of simple allylic alcohols or diversely functionalized ones (i.e., Morita-Baylis-Hillman alcohols) with 1,3-dicarbonyl compounds, under the catalysis of a variety of transition metals (Pd, Ir, Ru, Rh, Cu, Ni, Fe, Co, Au, Ag, Pt, W) and rare earth metals (Sc, La, Yb) complexes under activators-free conditions or in the presence of activators, as well as Lewis/Brønsted acids, and organocatalysts. In each synthetic process, a mechanistic aspect is proposed, along with a comparison of the observed regioselectivity in Pd-catalyzed allylic alkylations with that of other metals. Finally, numerous applications to the synthesis of complex molecules and natural products, are presented.