Iridium-Catalyzed 1,3-Rearrangement of Allylic Alcohols

The allylic alcohol structural motif is prevalent in many important molecules and valuable building blocks. The rearrangement reaction is one of the most important transformations, however there are only a few reports for the 1,3-rearrangement of allylic alcohols. Herein, a 1,3-rearrangement of allylic alcohols catalyzed by an Ir(III) dihydride complex is described. This reaction could provide the corresponding less accessible allylic alcohols regio- and stereoselectively from readily available E/Z mixtures of the substrates. Furthermore, a tandem alkene isomerization followed by 1,3-rearrangement of homoallylic alcohols was also realized. In addition, this rearrangement reaction could be used to synthesize the natural product Navenone B. Mechanistic investigation indicated that the reaction pathway involved a pi-allyl-Ir(V) intermediate and that the dihydride in the iridium catalyst acts as a hydrogen switch to modulate the valence of the iridium center.

Automated summary

Herein, a 1,3-rearrangement reaction of allylic alcohols catalyzed by an Ir(III) dihydride complex is described. The reaction selectively provides the corresponding less accessible allylic alcohols from E/Z mixtures of the substrates. Furthermore, a tandem alkene isomerization followed by 1,3-rearrangement of homoallylic alcohols was also achieved. The rearrangement reaction could be used to synthesize the natural product Navenone B. Mechanistic investigation revealed the involvement of a pi-allyl-Ir(V) intermediate and the modulation of iridium center valence by the dihydride in the iridium catalyst.