%0 Journal Article %A Selim, Khalid B. %A Nakanishi, Hirotsugu %A Matsumoto, Yasumasa %A Yamamoto, Yasutomo %A Yamada, Ken-ichi %A Tomioka, Kiyoshi %D 2011 %T Chiral N-Heterocyclic Carbene−Copper(I)-Catalyzed Asymmetric Allylic Arylation of Aliphatic Allylic Bromides: Steric and Electronic Effects on γ-Selectivity %U https://acs.figshare.com/articles/journal_contribution/Chiral_N_Heterocyclic_Carbene_Copper_I_Catalyzed_Asymmetric_Allylic_Arylation_of_Aliphatic_Allylic_Bromides_Steric_and_Electronic_Effects_on_Selectivity/2686627 %R 10.1021/jo102386s.s001 %2 https://acs.figshare.com/ndownloader/files/4355662 %K carbene ligand %K aryl group %K selectivity %K aryl Grignard reagents %K aliphatic allylic bromides %K Aliphatic Allylic Bromides %X Chiral N-heterocyclic carbene ligands were electronically and sterically tuned to improve γ-selectivity in copper(I)-catalyzed asymmetric allylic arylation of aliphatic allylic bromides with several aryl Grignard reagents. High γ-selectivity was realized when either the aryl group of the Grignard reagent or the aryl group on the N-substituent of the carbene ligand was electron-deficient or when either the carbene ligand or allylic bromide was bulky. The results indicated that electron deficiency and steric hindrance of the initially formed σ-allyl copper intermediate enhance the rate of the reductive elimination to give γ-products as major isomers. %I ACS Publications