Asymmetric Domino Aza-Michael Addition/[3+2] Cycloaddition Reactions as a Versatile Approach to alpha,beta,gamma,-Triamino Acid Derivatives
2014
Abstrakt
Nonproteinogenic amino acids are prepared by an unprecedented domino aza-Michael addition-1,3-dipolar cycloaddition, leading to enantiopure highly substituted pyrrolidinopyrazolines. Nonaflyl azide serves as highly effective diazo transfer reagent, forming the link between the conjugate addition and cycloaddition steps.
The resulting pyrrolidinopyrazolines can be rapidly transformed to either alpha,beta,gamma-triamino acids or 3,4-methano-beta-prolines. Peptide coupling can be regioselectively conducted at each of the amino groups.