Iridium‐Catalyzed Enantioselective Allylic Substitutions of Racemic, Branched Trichloroacetimidates with Heteroatom Nucleophiles: Formation of Allylic C−O, C−N, and C−S Bonds

Abstract

AbstractA broadly applicable methodology for the regio‐ and enantioselective construction of branched allylic carbon‐heteroatom bonds from racemic, secondary allylic trichloroacetimidates has been developed. The branched allylic substrates undergo dynamic kinetic asymmetric substitution reactions with a number of unactivated anilines and carboxylic acids as well as unactivated aromatic thiols in the presence of a chiral bicyclo[3.3.0]octadiene‐ligated iridium catalyst. The allylic C−O, C−N, and C−S bond containing products are obtained in synthetically useful yield and selectivity. Mechanistic studies suggest that the iridium‐catalyzed enantioselective substitution reactions of heteroatom nucleophiles with allylic trichloroacetimidate substrates through an outer‐sphere nucleophilic addition mechanism. In addition, the chiral diene‐ligated iridium catalyst is effective at promoting asymmetric aminations of acyclic secondary anilines. Importantly, this catalytic iridium methodology enables the use of alkyl substituted allylic electrophiles.magnified image