Beta-amino alcohol derived beta-hydroxy- and beta-(o-diphenylphosphino)benzoyloxy(o-diphenylphosphino)benzamides: an ester-amide ligand structural model for the palladium-catalyzed allylic alkylation reaction.
A commercially available collection of beta-amino alcohols have been converted to their corresponding beta-hydroxy- and beta-(o-diphenylphosphino)benzoyloxy(o-diphenylphosphino)benzamides 11a-f and 12a-f and have been employed in the Tsuji-Trost asymmetric alkylation reaction with 1,3-diphenylpropenyl acetate. With the exception of ligands 11b and 11f, the beta-hydroxybenzoyloxy(o-diphenylphosphino)benzamide ligands 11a-f primarily afforded the (R)-enantiomer of the product. In contrast, the bis(phosphine) ligands 12a-f consistently afforded the (S)-enantiomer. The best ligand (12c) was derived from cis-(1R,2S)-2-amino-1,2-diphenyl-1-ethanol, and when applied in the asymmetric allylic alkylation reaction, it yielded the product in an enantiomeric ratio of 97.8.22 favoring the (S)-enantiomer. A computational study was conducted on the conformation that this ligand might adopt in the palladium-catalyzed alkylation reaction as compared to that of the Trost ligand 1a.
Mahadik
Geetanjali S
GS
Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, USA.
Knott
Stanley A
SA
Szczepura
Lisa F
LF
Peters
Steven J
SJ
Standard
Jean M
JM
Hitchcock
Shawn R
SR