Fine-Tuning the Bicyclo[3.3.1]nona-2,6-diene Ligands: Second Generation 4,8-Substituted Dienes for Rh-Catalyzed Asymmetric 1,4-Addition Reactions

Article abstract of DOI:10.1002/cctc.202100638

Design and synthesis of the second generation C₂-symmetric 4,8-endo,endo-bis(alkoxy) bicyclo[3.3.1]nona-2,6-diene ligands possessing additional 4,8-exo,exo substituents is reported. The 4,8-exo,exo groups provide a further element for fine-tuning of the ligand structure by enforcing conformational rigidity of the 4,8-endo,endo side chains. Such tetrasubstituted bicyclo[3.3.1]nona-2,6-dienes were employed as steering ligands in the rhodium-catalyzed arylation of cyclic enones with arylboronic acids, providing the corresponding 1,4-addition products in good to excellent yields (69–99 %) and enantioselectivities up to 99 % ee.