1414648-99-9Relevant academic research and scientific papers
Asymmetric induction afforded by chiral azolylidene N-heterocyclic carbenes (NHC) catalysts
Strand, Ragnhild B.,Helgerud, Trygve,Solvang, Tina,Dolva, Amund,Sperger, Christian A.,Fiksdahl, Anne
, p. 1350 - 1359,10 (2012)
Screening studies of new chiral imidazolium and triazolium based NHC salts I-VIII as ligands in asymmetric organometallic catalysis and as organocatalysts showed that these catalysts efficiently promoted the reactions. Moderate enantioselectivities (55-57% ee) were obtained in the asymmetric Cu-NHC catalysed conjugate additions of diethylzinc to cyclohexenone, in accordance with most previous studies. The chiral induction afforded in the gold(I)-NHC catalysed cyclopropanation reactions was low (28% ee). However, these results represent the first reported chiral gold(I)-NHC catalysed olefin cyclopropanation. The NHC-organocatalysed asymmetric cross-annulation of cinnamaldehyde and trifluoroacetophenone gave lower enantioselectivity (50% ee) but higher yields of the γ-lactone product relative to previous reports. The enantioselectivities obtained varied considerably, even within a group of structurally closely related NHCs. This study demonstrates the challenge of designing NHCs with a general ability to induce asymmetry in a broader range of reactions.
Asymmetric induction afforded by chiral azolylidene N-heterocyclic carbenes (NHC) catalysts
Strand, Ragnhild B.,Helgerud, Trygve,Solvang, Tina,Dolva, Amund,Sperger, Christian A.,Fiksdahl, Anne
, p. 1350 - 1359 (2013/01/15)
Screening studies of new chiral imidazolium and triazolium based NHC salts I-VIII as ligands in asymmetric organometallic catalysis and as organocatalysts showed that these catalysts efficiently promoted the reactions. Moderate enantioselectivities (55-57% ee) were obtained in the asymmetric Cu-NHC catalysed conjugate additions of diethylzinc to cyclohexenone, in accordance with most previous studies. The chiral induction afforded in the gold(I)-NHC catalysed cyclopropanation reactions was low (28% ee). However, these results represent the first reported chiral gold(I)-NHC catalysed olefin cyclopropanation. The NHC-organocatalysed asymmetric cross-annulation of cinnamaldehyde and trifluoroacetophenone gave lower enantioselectivity (50% ee) but higher yields of the γ-lactone product relative to previous reports. The enantioselectivities obtained varied considerably, even within a group of structurally closely related NHCs. This study demonstrates the challenge of designing NHCs with a general ability to induce asymmetry in a broader range of reactions.
