Structural diversity using amino acid "Customizable Units": conversion of hydroxyproline (Hyp) into nitrogen...

Area of Science:

• Organic Chemistry
• Synthetic Chemistry
• Medicinal Chemistry

Background:

• Amino acids serve as versatile building blocks in organic synthesis.
• 4-hydroxyproline (Hyp) offers unique functional handles for chemical modification.
• Generating structural diversity is crucial for drug discovery and materials science.

Purpose of the Study:

• To explore the synthetic utility of 4-hydroxyproline (Hyp) for creating diverse nitrogen heterocycles.
• To develop a stereoselective method for synthesizing β-amino-δ-lactams and alkaloid/iminosugar derivatives.
• To showcase the potential of Hyp as a customizable unit for generating molecular complexity.

Main Methods:

• A one-pot decarboxylation-alkylation reaction of Hyp to yield 2-alkylpyrrolidines.
• Divergent synthetic pathways utilizing the 4-hydroxy group: radical scission or elimination.
• Tandem reductive amination-cyclization for β-amino-δ-lactam synthesis.
• Conversion of pyrrole derivatives into alkaloid and iminosugar scaffolds.

Main Results:

• High stereoselectivity was achieved in the formation of 2-alkylpyrrolidines.
• Aliphatic β-amino aldehydes were generated via radical scission.
• β-amino-δ-lactams with various N-substituents were synthesized.
• Pyrrole derivatives were efficiently converted into alkaloid and iminosugar derivatives with excellent stereoselectivity.

Conclusions:

• 4-hydroxyproline (Hyp) is a valuable precursor for generating diverse nitrogen heterocycles.
• The developed methodology provides access to rigidifying peptide units (β-amino-δ-lactams) and complex natural product scaffolds (alkaloids, iminosugars).
• This approach highlights the potential of amino acid-derived units for creating structural diversity in organic synthesis.