On the Asymmetric Iridium‐Catalyzed N‐Allylation of Amino Acid Esters: Improved Selectivities through Structural Variation of the Chiral Phosphoramidite Ligand
2022; Wiley; Volume: 2022; Issue: 12 Linguagem: Inglês
10.1002/ejoc.202200188
ISSN1434-193X
AutoresDominik Albat, Alicia S. Köcher, Julia Witt, Hans‐Günther Schmalz,
Tópico(s)Synthetic Organic Chemistry Methods
ResumoAbstract The investigation of the iridium‐catalyzed asymmetric N ‐allylation of tert ‐butyl glycinate using a “branched” racemic 1‐vinyl‐alkyl methyl carbonate revealed severe limitations of existing protocols. By screening a set of 24 BINOL‐derived chiral phosphoramidites a new superior ligand ( L24* ) was identified which afforded the amination product with high enantioselectivity (≥95 % ee) under optimized conditions. This ligand also allowed the N ‐allylation of other amino acid tert ‐butyl esters (derived from alanine, phenylalanine, or proline) with outstanding levels of diastereocontrol (d.r. ≥99 : 1) and negligible matched/mismatched differences.
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