Palladium-catalyzed δ-selective reductive Heck reaction of alkenyl carbonyl compounds with aryl iodides and bromides

Abstract

A palladium-catalyzed δ-selective reductive Heck reaction of 4-pentenoic acid derivatives bearing an 8-aminoquinoline directing group with aryl iodides and bromides has been developed. The reactions were carried out by using 5–10 mol% of Pd(OAc)₂ as the catalyst without the addition of external ligand in the presence of K₃PO₄ base in EtOH at 100 °C under air. Under these conditions both terminal and internal unactivated alkenes reacted smoothly with various aryl iodides and bromides to give a wide variety of δ-aryl pentanoic acid derivatives as single regioisomeric products in moderate to good yields. Deuterium-labeling experiments suggest that the ethanol serves as the hydride source in the reaction.