title: γ- and δ-lactams through palladium-catalyzed intramolecular allylic alkylation: enantioselective synthesis, NMR Investigation, and DFT rationalization.
abstract: The Pd-catalyzed intramolecular allylic alkylation of unsaturated amides to give γ- and δ-lactams has been studied in the presence of chiral ligands. Ligand (R)-3,5-tBu-MeOBIPHEP (MeOBIPHEP = 6,6'-dimethoxybiphenyl-2,2-diyl)bis(diphenylphosphine)) afforded the best results and allowed the cyclization reactions to take place in up to 94:6 enantiomeric ratio. A model Pd-allyl complex has been prepared and studied through NMR spectroscopic analysis, which provided insight into the processes responsible for the observed enantiomeric ratios. DFT studies were used to characterize the diastereomeric reaction pathways. The calculated energy differences were in good agreement with the experimentally observed enantiomeric ratios.
authors.affiliation: UPMC Univ Paris 06, Institut Parisien de Chimie Moléculaire (UMR CNRS 7201), FR2769, 4, Place Jussieu, 75252, case 183, 75005, Paris, France.
authors.forename: Xavier
authors.initials: X
authors.lastname: Bantreil
authors.forename: Guillaume
authors.initials: G
authors.lastname: Prestat
authors.forename: Aitor
authors.initials: A
authors.lastname: Moreno
authors.forename: David
authors.initials: D
authors.lastname: Madec
authors.forename: Peter
authors.initials: P
authors.lastname: Fristrup
authors.forename: Per-Ola
authors.initials: PO
authors.lastname: Norrby
authors.forename: Paul S
authors.initials: PS
authors.lastname: Pregosin
authors.forename: Giovanni
authors.initials: G
authors.lastname: Poli