Solid-phase route to Fmoc-protected cationic amino acid building blocks.

Area of Science:

• Organic Chemistry
• Medicinal Chemistry
• Peptide Synthesis

Background:

• Diamino acids are crucial components of bioactive molecules.
• Limited commercial availability of diamino acid building blocks hinders peptide synthesis.
• Need for versatile and cost-effective methods to synthesize functionalized amino acids.

Purpose of the Study:

• To develop an efficient and inexpensive solid-phase synthesis for novel diamino acid building blocks.
• To create building blocks with tunable hydrophobicity and multiple positive charges.
• To demonstrate the utility of these building blocks in peptide synthesis.

Main Methods:

• A versatile solid-phase protocol involving (S)-1-(p-nosyl)aziridine-2-methanol and a trityl bromide resin.
• On-resin protection, protecting group exchange, and cleavage from the resin.
• Solution-phase oxidation to yield γ-aza substituted diamino acid building blocks with Fmoc/Boc protection.

Main Results:

• Gram-scale synthesis of selectively protected amino alcohol intermediates.
• Successful preparation of diverse γ-aza substituted diamino acid analogs, including bulky and polycationic variants.
• Incorporation of two novel building blocks into peptide sequences via microwave-assisted solid-phase peptide synthesis.

Conclusions:

• The developed strategy provides a convenient and inexpensive route to valuable diamino acid building blocks.
• The synthesized building blocks are suitable for constructing peptides with multiple positive charges and varied hydrophobicity.
• This method broadens the scope of available building blocks for advanced peptide-based drug discovery and materials science.