Rhodium-Catalyzed Dynamic Kinetic Asymmetric Allylation of Phenols and 2-Hydroxypyridines.
Inspired by the mechanistic studies of rhodium-catalyzed atom-economic addition of carboxylate acids to allenes, a rhodium-catalyzed dynamic kinetic asymmetric allylation of different nucleophiles with racemic allylic carbonates has been developed. High regio- and enantioselectivities can be obtained under neutral conditions and, furthermore, the chemoselectivities can be controlled by different diphosphine ligands. (R,R)-QuinoxP* leads to selective O-allylation of phenols, whereas when embedding (S,S)-DIOP as the ligand, 2-naphthol is ortho-C-allylated for the first time in high enantioselectivity. To this end, hydroxypyridines can be N-allylated by Rh(I) /(S)-DTBM-Segphos via the same intermediate as in the previously reported atom-economic addition to allenes.
Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany.
Changkun
C
Li
Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg im Breisgau, Germany. bernhard.breit@chemie.uni-freiburg.de.
Bernhard
http://orcid.org/0000-0002-2514-3898
B
Breit
allylic substitution; dynamic kinetic asymmetric transformations; enantioselectivity; phenol; rhodium